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Sample records for elemental ions released

  1. Elemental ion release from fixed restorative materials into patient saliva.

    PubMed

    Elshahawy, W; Ajlouni, R; James, W; Abdellatif, H; Watanabe, I

    2013-05-01

    The objective of this study was to quantitatively investigate the elemental ion release from the fixed gold alloy and ceramic crowns into patient saliva. Twenty patients who participated in the study were divided into two equal groups; 1) full coverage type IV gold crowns and 2) full coverage CAD-CAM-fabricated ceramic crowns. Saliva collection and clinical evaluation of marginal integrity and gingival health were performed before crowns preparation, 3 months and 6 months after crowns placement. Clinical evaluations were conducted using California Dental Association criteria. Collected saliva samples were analysed for element release using inductively coupled plasma mass spectrometer. The zinc, copper, palladium, gold and silver were released from type IV gold crowns into saliva, while the silicon and aluminium were released from ceramic crowns. A clinically significant number of subjects had increased release of zinc from baseline to three-month recall and increased silicon release from baseline to both three-month and six-month recalls. For all elements, the subjects' counts for the case of three-month recall to six-month recall were never higher than that of the case of baseline to three-month recall except for palladium. No obvious adverse effects on marginal integrity or gingival health were noticed. Significant increased releases of zinc from cast gold crowns and silicon from CAD-CAM-fabricated ceramic crowns into the saliva were evident after 3 months of clinical service.

  2. CORONAL SOURCES, ELEMENTAL FRACTIONATION, AND RELEASE MECHANISMS OF HEAVY ION DROPOUTS IN THE SOLAR WIND

    SciTech Connect

    Weberg, Micah J.; Lepri, Susan T.; Zurbuchen, Thomas H. E-mail: slepri@umich.edu

    2015-03-10

    The elemental abundances of heavy ions (masses larger than He) in the solar wind provide information about physical processes occurring in the corona. Additionally, the charge state distributions of these heavy ions are sensitive to the temperature profiles of their respective source regions in the corona. Heavy ion dropouts are a relatively new class of solar wind events identified by both elemental and ionic charge state distributions. We have shown that their origins lie in large, closed coronal loops where processes such as gravitational settling dominate and can cause a mass-dependent fractionation pattern. In this study we consider and attempt to answer three fundamental questions concerning heavy ion dropouts: (1) 'where are the source loops located in the large-scale corona?'; (2) 'how does the interplay between coronal processes influence the end elemental abundances?'; and (3) 'what are the most probable release mechanisms'? We begin by analyzing the temporal and spatial variability of heavy ion dropouts and their correlation with heliospheric plasma and magnetic structures. Next we investigate the ordering of the elements inside dropouts with respect to mass, ionic charge state, and first ionization potential. Finally, we discuss these results in the context of the prevailing solar wind theories and the processes they posit that may be responsible for the release of coronal plasma into interplanetary space.

  3. The impact of nanosilver addition on element ions release form light-cured dental composite and compomer into 0.9% NaCl.

    PubMed

    Sokołowski, Krzysztof; Szynkowska, Małgorzata I; Pawlaczyk, Aleksandra; Łukomska-Szymańska, Monika; Sokołowski, Jerzy

    2014-01-01

    The aim of this paper was to identify and to assess in semi-quantified way the release of different ions from composite and compomer restorative materials subjected to 0.9% NaCl solution, which simulates the environment of the human body. In the present study, the number of ions (Al, Ag, Ba, Sr, Ti) released from dental fillings over time (one week, one month and 3 months), in different temperatures (23°C, 37°C) and depending on the materials applied (unmodified/modified with nanosilver) was investigated. The results suggest that nanosilver addition influences directly on the process of metal ion releasing into 0.9% NaCl solution. The increase in the number of counts of metal ions was observed in the solutions in which samples modified with nanosilver were kept. Higher amount of metal ion release was observed for composite samples rather than for compomer materials. The study revealed that in general the number of released metal ions increases with the time of storage (for metal ions: Ti, Ba, Sr) and at higher temperature (Ag, Ti, Ba). Reverse tendency observed for silver ion release versus incubation time may be caused by the process of silver adsorption, which takes place on the surface of analyzed material and test-tube walls, where samples were incubated.

  4. Tool Releases Optical Elements From Spring Brackets

    NASA Technical Reports Server (NTRS)

    Gum, J. S.

    1984-01-01

    Threaded hooks retract bracket arms holding element. Tool uses three hooks with threaded shanks mounted in ring-shaped holder to pull on tabs to release optical element. One person can easily insert or remove optical element (such as prism or lens) from spring holder or bracket with minimal risk of damage.

  5. Composite oxygen ion transport element

    DOEpatents

    Chen, Jack C.; Besecker, Charles J.; Chen, Hancun; Robinson, Earil T.

    2007-06-12

    A composite oxygen ion transport element that has a layered structure formed by a dense layer to transport oxygen ions and electrons and a porous support layer to provide mechanical support. The dense layer can be formed of a mixture of a mixed conductor, an ionic conductor, and a metal. The porous support layer can be fabricated from an oxide dispersion strengthened metal, a metal-reinforced intermetallic alloy, a boron-doped Mo.sub.5Si.sub.3-based intermetallic alloy or combinations thereof. The support layer can be provided with a network of non-interconnected pores and each of said pores communicates between opposite surfaces of said support layer. Such a support layer can be advantageously employed to reduce diffusion resistance in any type of element, including those using a different material makeup than that outlined above.

  6. FORTE antenna element and release mechanism design

    NASA Technical Reports Server (NTRS)

    Rohweller, David J.; Butler, Thomas A.

    1995-01-01

    The Fast On-Orbit Recording of Transient Events (FORTE) satellite being built by Los Alamos National Laboratory (LANL) and Sandia National Laboratories (SNL) has as its most prominent feature a large deployable (11 m by 5 m) log periodic antenna to monitor emissions from electrical storms on the Earth. This paper describes the antenna and the design for the long elements and explains the dynamics of their deployment and the damping system employed. It also describes the unique paraffin-actuated reusable tie-down and release mechanism employed in the system.

  7. Ion processing element with composite media

    DOEpatents

    Mann, Nick R.; Tranter, Troy J.; Todd, Terry A.; Sebesta, Ferdinand

    2009-03-24

    An ion processing element employing composite media disposed in a porous substrate, for facilitating removal of selected chemical species from a fluid stream. The ion processing element includes a porous fibrous glass substrate impregnated by composite media having one or more active components supported by a matrix material of polyacrylonitrile. The active components are effective in removing, by various mechanisms, one or more constituents from a fluid stream passing through the ion processing element. Due to the porosity and large surface area of both the composite medium and the substrate in which it is disposed, a high degree of contact is achieved between the active component and the fluid stream being processed. Further, the porosity of the matrix material and the substrate facilitates use of the ion processing element in high volume applications where it is desired to effectively process a high volume flows.

  8. Ion processing element with composite media

    DOEpatents

    Mann, Nick R.; Tranter, Troy J.; Todd, Terry A.; Sebesta, Ferdinand

    2003-02-04

    An ion processing element employing composite media disposed in a porous substrate, for facilitating removal of selected chemical species from a fluid stream. The ion processing element includes a porous fibrous glass substrate impregnated by composite media having one or more active components supported by a matrix material of polyacrylonitrile. The active components are effective in removing, by various mechanisms, one or more constituents from a fluid stream passing through the ion processing element. Due to the porosity and large surface area of both the composite medium and the substrate in which it is disposed, a high degree of contact is achieved between the active component and the fluid stream being processed. Further, the porosity of the matrix material and the substrate facilitates use of the ion processing element in high volume applications where it is desired to effectively process a high volume flows.

  9. Plasma immersion ion implantation for reducing metal ion release

    SciTech Connect

    Diaz, C.; Garcia, J. A.; Maendl, S.; Pereiro, R.; Fernandez, B.; Rodriguez, R. J.

    2012-11-06

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  10. Plasma immersion ion implantation for reducing metal ion release

    NASA Astrophysics Data System (ADS)

    Díaz, C.; García, J. A.; Mändl, S.; Pereiro, R.; Fernández, B.; Rodríguez, R. J.

    2012-11-01

    Plasma immersion ion implantation of Nitrogen and Oxygen on CoCrMo alloys was carried out to improve the tribological and corrosion behaviors of these biomedical alloys. In order to optimize the implantation results we were carried experiments at different temperatures. Tribocorrosion tests in bovine serum were used to measure Co, Cr and Mo releasing by using Inductively Coupled Plasma Mass Spectrometry analysis after tests. Also, X-ray Diffraction analysis were employed in order to explain any obtained difference in wear rate and corrosion tests. Wear tests reveals important decreases in rate of more than one order of magnitude for the best treatment. Moreover decreases in metal release were found for all the implanted samples, preserving the same corrosion resistance of the unimplanted samples. Finally this paper gathers an analysis, in terms of implantation parameters and achieved properties for industrial implementation of these treatments.

  11. Ammonium and sulfate ion release of histamine from lung fragments.

    PubMed

    Charles, J M; Menzel, D B

    1975-06-01

    In vitro studies with guinea pig lung fragments incubated with 10- to 200-mM concentrations of ammonium ion demonstrated the release of substanial quantities of histamine. Of the anions tested with ammonium ion, sulfate was the most potent, while nitrate and acetate ions were of intermediate potency and chloride was less potent. An osmotic effect is unlikely since equal concentrations of sodium chloride failed to release histamine. Isoproterenol, known to decrease anaphylactic histamine release, and acetycholine, known to increase histamine release, had no effect on the ammonium sulfate-mediated release of histamine. N-6 2'-O-Dibutyryladenosine 3',5' monophosphate (dibutyryl c-AMP) was also ineffective. These studies suggest that the inhalation irritation associated with certain sulfate and other salts, may be a function of their ability to release histamine in the presence of amonium ion.

  12. Rechargeable calcium phosphate orthodontic cement with sustained ion release and re-release

    NASA Astrophysics Data System (ADS)

    Zhang, Ling; Weir, Michael D.; Chow, Laurence C.; Reynolds, Mark A.; Xu, Hockin H. K.

    2016-11-01

    White spot lesions (WSL) due to enamel demineralization are major complications for orthodontic treatments. Calcium phosphate (CaP) dental resins with Ca and P ion releases are promising for remineralization. However, previous Ca and P releases lasted for only weeks. Experimental orthodontic cements were developed using pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at mass ratio of 1:1 (PE); and PE plus 10% of 2-hydroxyethyl methacrylate (HEMA) and 5% of bisphenol A glycidyl dimethacrylate (BisGMA) (PEHB). Particles of amorphous calcium phosphate (ACP) were incorporated into PE and PEHB at 40% filler level. Specimens were tested for bracket-enamel shear bond strength, water sorption, CaP release, and ion recharge and re-release. PEHB+40ACP had higher bracket-enamel bond strength and ion release and rechargeability than PE+40ACP. ACP incorporation into the novel orthodontic cement did not adversely affect the bracket-enamel bond strength. Ion release and re-release from the novel ACP orthodontic cement indicated favorable release and re-release patterns. The recharged orthodontic cement could release CaP ions continuously for four weeks without further recharge. Novel rechargeable orthodontic cement containing ACP was developed with a high bracket-enamel bond strength and the ability to be repeatedly recharged to maintain long-term high levels of CaP ion releases.

  13. Rechargeable calcium phosphate orthodontic cement with sustained ion release and re-release

    PubMed Central

    Zhang, Ling; Weir, Michael D.; Chow, Laurence C.; Reynolds, Mark A.; Xu, Hockin H. K.

    2016-01-01

    White spot lesions (WSL) due to enamel demineralization are major complications for orthodontic treatments. Calcium phosphate (CaP) dental resins with Ca and P ion releases are promising for remineralization. However, previous Ca and P releases lasted for only weeks. Experimental orthodontic cements were developed using pyromellitic glycerol dimethacrylate (PMGDM) and ethoxylated bisphenol A dimethacrylate (EBPADMA) at mass ratio of 1:1 (PE); and PE plus 10% of 2-hydroxyethyl methacrylate (HEMA) and 5% of bisphenol A glycidyl dimethacrylate (BisGMA) (PEHB). Particles of amorphous calcium phosphate (ACP) were incorporated into PE and PEHB at 40% filler level. Specimens were tested for bracket-enamel shear bond strength, water sorption, CaP release, and ion recharge and re-release. PEHB+40ACP had higher bracket-enamel bond strength and ion release and rechargeability than PE+40ACP. ACP incorporation into the novel orthodontic cement did not adversely affect the bracket-enamel bond strength. Ion release and re-release from the novel ACP orthodontic cement indicated favorable release and re-release patterns. The recharged orthodontic cement could release CaP ions continuously for four weeks without further recharge. Novel rechargeable orthodontic cement containing ACP was developed with a high bracket-enamel bond strength and the ability to be repeatedly recharged to maintain long-term high levels of CaP ion releases. PMID:27808251

  14. Ion permeable microcapsules for the release of biologically available ions for remineralization.

    PubMed

    Davidson, Michael T; Greving, Theresa A; McHale, William A; Latta, Mark A; Gross, Stephen M

    2012-03-01

    The objective of this study was to investigate the effect of chemical structure, ion concentration, and ion type on the release rate of biologically available ions useful for remineralization from microcapsules with ion permeable membranes. A heterogeneous polymerization technique was utilized to prepare microcapsules containing either an aqueous solution of K₂HPO₄, Ca(NO₃)₂, or NaF. Six different polyurethane-based microcapsule shells were prepared and characterized based on ethylene glycol, butanediol, hexanediol, octanediol, triethylene glycol, and bisphenol A structural units. Ion release profiles were measured as a function of initial ion concentration within the microcapsule, ion type, and microcapsule chemical structure. The rate of ion release increased with initial concentration of ion stored in the microcapsule over a range of 0.5-3.0M. The monomer used in the synthesis of the membrane had a significant effect on ion release rates at 3.0 M salt concentration. At 1.0 M, the ethylene glycol released ions significantly faster than the hexanediol-, octanediol-, and butanediol-based microcapsules. Ion release was fastest for fluoride and slowest for phosphate for the salts used in this study. It was concluded that the microcapsules are capable of releasing calcium, phosphate, and fluoride ions in their biologically available form.

  15. Transport of ions injected by AMPTE magnetotail releases

    NASA Technical Reports Server (NTRS)

    Cladis, J. B.; Francis, W. E.

    1989-01-01

    The BA and Li ions released in the magnetotail by the AMPTE IRM satellite were not observed in the inner magnetosphere with the AMPTE CCE satellite. In an effort to understand these results, Cladis and Francis (1988) modeled the expansion and ionization of the released atoms and computed several hundred guiding-center trajectories of the ions to sample the motion of each ion cloud. Here, the transport calculations are improved, principally by computing the full gyration motion of the ions in a more realistic model of the geomagnetic tail. The results indicate that the Ba(+) ions were convected inward along a narrow corridor, which was at least 2 earth radii away from the satellite in the case of the first Ba release and at least 3 earth radii away in the case of the second Ba release. Even if the ions had reached the satellite, their energies would have been too low to be detected. The Li(+) ions from both releases drifted inward over broad regions which overlapped the satellite in space and time. However, their fluxes at the satellite were somewhat too low to be detected.

  16. Synthesis and release of trace elements from hollow and porous hydroxyapatite spheres.

    PubMed

    Xia, Wei; Grandfield, Kathryn; Schwenke, Almut; Engqvist, Håkan

    2011-07-29

    It is known that organic species regulate fabrication of hierarchical biological forms via solution methods. However, in this study, we observed that the presence of inorganic ions plays an important role in the formation and regulation of biological spherical hydroxyapatite formation. We present a mineralization method to prepare ion-doped hydroxyapatite spheres with a hierarchical structure that is free of organic surfactants and biological additives. Porous and hollow strontium-doped hydroxyapatite spheres were synthesized via controlling the concentration of strontium ions in a calcium and phosphate buffer solution. Similarly, fluoride and silicon-doped hydroxyapatite spheres were synthesized. While spherical particle formation was attainable at low and high temperature for Sr-doped hydroxyapatite, it was only possible at high temperature in the F/Si-doped system. The presence of inorganic ions not only plays an important role in the formation and regulation of biological spherical hydroxyapatite, but also could introduce pharmaceutical effects as a result of trace element release. Such ion release results showed a sustained release with pH responsive behavior, and significantly influenced the hydroxyapatite re-precipitation. These ion-doped hydroxyapatite spheres with hollow and porous structure could have promising applications as bone/tooth materials, drug delivery systems, and chromatography supports.

  17. Selective coulometric release of ions from ion selective polymeric membranes for calibration-free titrations.

    PubMed

    Bhakthavatsalam, Vishnupriya; Shvarev, Alexey; Bakker, Eric

    2006-08-01

    Coulometry belongs to one of the few known calibration-free techniques and is therefore highly attractive for chemical analysis. Titrations performed by the coulometric generation of reactants is a well-known approach in electrochemistry, but suffers from limited selectivity and is therefore not generally suited for samples of varying or unknown composition. Here, the selective coulometric release of ionic reagents from ion-selective polymeric membrane materials ordinarily used for the fabrication of ion-selective electrodes is described. The selectivity of such membranes can be tuned to a significant extent by the type and concentration of ionophore and lipophilic ion-exchanger and is today well understood. An anodic current of fixed magnitude and duration may be imposed across such a membrane to release a defined quantity of ions with high selectivity and precision. Since the applied current relates to a defined ion flux, a variety of non-redox active ions may be accurately released with this technique. In this work, the released titrant's activity was measured with a second ionophore-based ion-selective electrode and corresponded well with expected dosage levels on the basis of Faraday's law of electrolysis. Initial examples of coulometric titrations explored here include the release of calcium ions for complexometric titrations, including back titrations, and the release of barium ions to determine sulfate.

  18. Quantifying the origin of released Ag+ ions from nanosilver.

    PubMed

    Sotiriou, Georgios A; Meyer, Andreas; Knijnenburg, Jesper T N; Panke, Sven; Pratsinis, Sotiris E

    2012-11-13

    Nanosilver is most attractive for its bactericidal properties in modern textiles, food packaging, and biomedical applications. Concerns, however, about released Ag(+) ions during dispersion of nanosilver in liquids have limited its broad use. Here, nanosilver supported on nanostructured silica is made with closely controlled Ag size both by dry (flame aerosol) and by wet chemistry (impregnation) processes without any surface functionalization that could interfere with its ion release. It is characterized by electron microscopy, atomic absorption spectroscopy, and X-ray diffraction, and its Ag(+) ion release in deionized water is monitored electrochemically. The dispersion method of nanosilver in solutions affects its dissolution rate but not the final Ag(+) ion concentration. By systematically comparing nanosilver size distributions to their equilibrium Ag(+) ion concentrations, it is revealed that the latter correspond precisely to dissolution of one to two surface silver oxide monolayers, depending on particle diameter. When, however, the nanosilver is selectively conditioned by either washing or H(2) reduction, the oxide layers are removed, drastically minimizing Ag(+) ion leaching and its antibacterial activity against E. coli . That way the bactericidal activity of nanosilver is confined to contact with its surface rather than to rampant ions. This leads to silver nanoparticles with antibacterial properties that are essential for medical tools and hospital applications.

  19. Ion capturing/ion releasing films and nanoparticles in liquid crystal devices

    NASA Astrophysics Data System (ADS)

    Garbovskiy, Yuriy

    2017-01-01

    Nanoparticles dispersed in liquid crystals can change the concentration of mobile ions through the adsorption/desorption process. In the majority of the reported cases, the effects of nanoparticles on the electrical properties of liquid crystals are analysed, neglecting the interactions of ions with substrates. In this paper, the combined effect of nanoparticles and substrates on the concentration of ions in liquid crystals is discussed. Depending on the ionic purity of substrates and nanoparticles, the ion capturing/ion releasing regimes can be achieved. In addition, the concentration of mobile ions in liquid crystal nanocolloids also depends on the cell thickness.

  20. Release of metal ions from orthodontic appliances: an in vitro study.

    PubMed

    Mikulewicz, Marcin; Chojnacka, Katarzyna; Woźniak, Barbara; Downarowicz, Patrycja

    2012-05-01

    In this paper, we report the results of an in vitro experiment on the release of metal ions from orthodontic appliances composed of alloys containing iron, chromium, nickel, silicon, and molybdenum into artificial saliva. The concentrations of magnesium, aluminum, silicon, phosphorus, sulfur, potassium, calcium, titanium, vanadium, manganese, iron, cobalt, copper, zinc, nickel, and chromium were significantly higher in artificial saliva in which metal brackets, bands, and wires used in orthodontics were incubated. In relation to the maximum acceptable concentrations of metal ions in drinking water and to recommended daily doses, two elements of concern were nickel (573 vs. 15 μg/l in the controls) and chromium (101 vs. 8 μg/l in the controls). Three ion release coefficients were defined: α, a dimensionless multiplication factor; β, the difference in concentrations (in micrograms per liter); and γ, the ion release coefficient (in percent). The elevated levels of metals in saliva are thought to occur by corrosion of the chemical elements in the alloys or welding materials. The concentrations of some groups of dissolved elements appear to be interrelated.

  1. Reversible Capture and Release of Elemental Halogens with a Redox-Active Metal-Organic Framework.

    PubMed

    Tulchinsky, Yuri; Hendon, Christopher H; Lomachenko, Kirill A; Borfecchia, Elisa; Melot, Brent C; Hudson, Matthew R; Tarver, Jacob D; Korzynski, Maciej D; Stubbs, Amanda W; Kagan, Jacob J; Lamberti, Carlo; Brown, Craig M; Dinca, Mircea

    2017-03-28

    Extreme toxicity, corrosiveness, and volatility pose serious challenges for the safe storage and transportation of elemental chlorine and bromine, which play critical roles in the chemical industry. Solid materials capable of forming stable non-volatile compounds upon reaction with elemental halogens may partially mitigate these challenges by allowing safe halogen release on demand. Here, we demonstrate that elemental halogens quantitatively oxidize coordinatively unsaturated Co(II) ions in a robust azolate metal-organic framework (MOF) to produce an air-stable and safe-to-handle Co(III) material featuring terminal Co(III)-halogen bonds. Thermal treatment of the oxidized MOF causes homolytic cleavage of the Co(III)-halogen bonds, reduction to Co(II), and concomitant release of elemental halogens. Remarkably, the reversible chemical storage and thermal release of elemental halogens occur with no significant losses of structural integrity, the parent cobaltous MOF retaining crystallinity and porosity even after three oxidation/reduction cycles. These results highlight a material operating via redox mechanism that may find utility in the storage and capture of other noxious and corrosive gases.

  2. Helium-ion-induced release of hydrogen from graphite

    SciTech Connect

    Langley, R.A.

    1987-01-01

    The ion-induced release of hydrogen from AXF-5Q graphite was studied for 350-eV helium ions. The hydrogen was implanted into the graphite with a low energy (approx.200 eV) and to a high fluence. This achieved a thin (approx.10-nm), saturated near-surface region. The release of hydrogen was measured as a function of helium fluence. A model that includes ion-induced detrapping, retrapping, and surface recombination was used to analyze the experimental data. A value of (1.65 +- 0.2) x 10/sup -16/ cm/sup 2/ was obtained from the detrapping cross section, and a value of (0.5 to 4) x 10/sup -14/ cm/sup 4//atoms was obtained for the recombination coefficient. 11 refs., 4 figs.

  3. Micro faraday-element array detector for ion mobility spectroscopy

    DOEpatents

    Gresham, Christopher A.; Rodacy, Phillip J.; Denton, M. Bonner; Sperline, Roger

    2004-10-26

    An ion mobility spectrometer includes a drift tube having a collecting surface covering a collecting area at one end of the tube. The surface comprises a plurality of closely spaced conductive elements on a non-conductive substrate, each conductive element being electrically insulated from each other element. A plurality of capacitive transimpedance amplifiers (CTIA) adjacent the collecting surface are electrically connected to the plurality of elements, so charge from an ion striking an element is transferred to the capacitor of the connected CTIA. A controller counts the charge on the capacitors over a period of time.

  4. Silver ion release from antimicrobial polyamide/silver composites.

    PubMed

    Kumar, Radhesh; Münstedt, Helmut

    2005-05-01

    Silver ion (Ag(+)) the versatile antimicrobial species was released in a steady and prolonged manner from a silver-filled polyamide composite system. Metallic silver powder having varying specific surface area (SSA) has been used as a resource of biocide in polyamide. Strong evidences are found showing the release of the antimicrobial species from the resulting composite upon soaking it in water due to the interaction of the diffused water molecules with the dispersed silver powder within the matrix. The Ag(+) release was observed as increasing with time and concentration of the silver powder and is found to be influenced by the SSA of the silver powder, changes in the physical state of the composite specimen as a result of the water diffusion and the composite morphology. It is observed that the Ag(+) release increases initially which is followed by a marginal increase between day 4 and 6. Composites containing higher amounts of silver (4 and 8 wt%) exhibit a further rise in Ag(+) release from the sixth day of storage in water. Composite containing silver particles with the lowest specific surface area (0.78 m(2)/g) showed highest Ag(+) release. SEM shows a finer dispersion of the silver powder (4 wt%) having lowest SSA. However particles with higher (1.16 and 2.5 m(2)/g) SSA possess an agglomerated morphology leading to lower Ag(+) release. The composites are found to release Ag(+) at a concentration level capable of rendering an antimicrobial efficacy.

  5. Zoledronate and Ion-releasing Resins Impair Dentin Collagen Degradation

    PubMed Central

    Tezvergil-Mutluay, A.; Seseogullari-Dirihan, R.; Feitosa, V.P.; Tay, F.R.; Watson, T.F.; Pashley, D.H.; Sauro, S.

    2014-01-01

    This study analyzed the amounts of solubilized telopeptides cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and C-terminal crosslinked telopeptide of type I collagen (CTX) derived from matrix-metalloproteinases (MMPs) and cysteine cathepsins (CTPs) subsequent to application of a filler-free (Res.A) or an ion-releasing resin (Res.B) to ethylenediaminetetraacetic acid (EDTA)-demineralized dentin with or without zoledronate-containing primer (Zol-primer) pre-treatment. The chemical modification induced following treatments and artificial saliva (AS) storage was also analyzed through attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). Totally EDTA-demineralized specimens were infiltrated with Res.A or Res.B with or without Zol-primer pre-treatment, light-cured, and immersed in AS for up to 4 wk. ICTP release was reduced following infiltration with Res.B and further reduced when Res.B was used with Zol-primer; remarkable phosphate mineral uptake was attained after AS storage. CTX release was increased in Res.A- and Res.B-treated dentin. However, when Zol-primer was used with Res.A, the CTX release fell significantly compared to the other tested resin-infiltration methods. In conclusion, zoledronate offers an additional inhibitory effect to the ion-releasing resins in MMP-mediated collagen degradation. However, Zol-primer induces a modest reduction in CTX release only when used with resin-based systems containing no ion-releasing fillers. PMID:25074494

  6. Approaches for Controlled Ag(+) Ion Release: Influence of Surface Topography, Roughness, and Bactericide Content.

    PubMed

    Sukhorukova, I V; Sheveyko, A N; Shvindina, N V; Denisenko, E A; Ignatov, S G; Shtansky, D V

    2017-02-01

    Silver is the most famous bactericidal element known from ancient times. Its antibacterial and antifungal effects are typically associated with the Ag ionization and concentration of Ag(+) ions in a bacterial culture. Herein we thoroughly studied the influence of surface topography and roughness on the rate of Ag(+) ion release. We considered two types of biocompatible and bioactive TiCaPCON-Ag films with 1 and 2 at. % of Ag and nine types of Ti surfaces with an average roughness varying in the range from 5.4 × 10(-2) to 12.6 μm and different topographic features obtained through polishing, sandblasting, laser treatment, and pulsed electrospark deposition. It is demonstrated that the Ag(+) ion release rates do not depend on the Ag content in the films as the main parameter, and it is other factors, such as the state of Ag agglomeration, surface topography and roughness, as well as kinetics of surface oxidation, that play a critical role. The obtained results clearly show a synergistic effect of the Ag content in the film and surface topography and roughness on Ag(+) ion release. By changing the surface topographical features at a constant content of bactericidal element, we showed that the Ag(+) ion release can be either accelerated by 2.5 times or almost completely suppressed. Despite low Ag(+) ion concentration in physiological solution (<40 ppb), samples with specially fabricated surface reliefs (flakes or holes) showed a pronounced antibacterial effect already after 3 h of immersion in E. coli bacterial culture. Thus, our results open up new possibilities for the production of cost-effective, scalable, and biologically safe implants with pronounced antibacterial characteristics for future applications in the orthopedic field.

  7. Ion release and cytotoxicity of stainless steel wires.

    PubMed

    Oh, Keun-Taek; Kim, Kyoung-Nam

    2005-12-01

    Heat treatment is generally applied to orthodontic stainless steel (SS) wires to relieve the stresses that result from their manipulation by orthodontists. The quality and thickness of the oxide films formed on the surface of heat-treated wires can vary, and it is believed that these oxide films can influence the properties of heat-treated wires. The aim of this study was to investigate the influence of heat treatment and cooling methods on the amount of metal ions released and to examine the cytotoxicity of heat-treated wires. In this study, four types of SS wires (Remanium, Permachrome, Colboloy and Orthos) with a cross-sectional area of 0.41 x 0.56 mm were investigated. These wires were heat-treated in a vacuum, air, or argon environment, and were cooled in either a furnace or a water bath. Four control groups and 24 experimental groups were classified according to the type of wires, heat treatment conditions and cooling methods. In each group, the amount of nickel released as well as its cytotoxicity was investigated. The concentration of dissolved nickel ions in artificial saliva was measured for a period of up to 12 weeks. In all groups, the concentration of dissolved nickel ions in artificial saliva was lowest for the vacuum heat treatment-furnace cooling group and a significant difference was shown compared with the other experimental groups. The concentration of dissolved nickel ions in artificial saliva was highest in the groups heat-treated in air (P < 0.05), while the amount of nickel released was highest in the Remanium and Colboloy (P < 0.05). The cytotoxicity was mild in all the experimental groups but the response index of the air groups was slightly higher than in the other groups. According to these results, SS wires retain their high corrosion resistance and low ion release rate when heat-treated in a vacuum and cooled in a furnace.

  8. Computational modelling of local calcium ions release from calcium phosphate-based scaffolds.

    PubMed

    Manhas, Varun; Guyot, Yann; Kerckhofs, Greet; Chai, Yoke Chin; Geris, Liesbet

    2017-04-01

    A variety of natural or synthetic calcium phosphate (CaP)-based scaffolds are currently produced for dental and orthopaedic applications. These scaffolds have been shown to stimulate bone formation due to their biocompatibility, osteoconductivity and osteoinductivity. The release of the [Formula: see text] ions from these scaffolds is of great interest in light of the aforementioned properties. It can depend on a number of biophysicochemical phenomena such as dissolution, diffusion and degradation, which in turn depend on specific scaffold characteristics such as composition and morphology. Achieving an optimal release profile can be challenging when relying on traditional experimental work alone. Mathematical modelling can complement experimentation. In this study, the in vitro dissolution behaviour of four CaP-based scaffold types was investigated experimentally. Subsequently, a mechanistic finite element method model based on biophysicochemical phenomena and specific scaffold characteristics was developed to predict the experimentally observed behaviour. Before the model could be used for local [Formula: see text] ions release predictions, certain parameters such as dissolution constant ([Formula: see text]) and degradation constant ([Formula: see text]) for each type of scaffold were determined by calibrating the model to the in vitro dissolution data. The resulting model showed to yield release characteristics in satisfactory agreement with those observed experimentally. This suggests that the mathematical model can be used to investigate the local [Formula: see text] ions release from CaP-based scaffolds.

  9. Microbial release of sulphur ions from atmospheric pollution deposits

    SciTech Connect

    Killhan, K.; Wainwright, M.

    1981-12-01

    The surfaces of leaves of Acer pseudoplatanus growing in areas exposed to heavy atmospheric pollution are covered with atmospheric pollution deposits (APD). Using scanning electron microscopy, micro-organisms were seen to be growing in intimate association with these deposits. The deposits contained sufficient carbon and nitrogen to support growth of the fungus Fusarium solani in culture and in autoclaved and non-sterilized soils; and sufficient reduced sulphur for the in vitro growth of Thiobacillus thioparus. When T. thioparus and F. solani were grown in medium supplemented with APD as sole carbon and nitrogen sources, increases in the concentrations of soluble S/sub 2/O/sup 2 -//sub 3/; S/sub 4/O/sup 2 -//sub 6/ and SO/sup 2 -//sub 4/ resulted. Similar increases also occurred when APD was added to complete fungal growth medium. Increases in LiCl/sub 2/-extractable sulphur-ions also occurred in fresh soil amended with APD, and in autoclaved soils containing APD, and inoculated with spores of F. solani. Arylsulphatase activity increased in fresh soils and in soils autoclaved and inoculated with F. solani when APD was added; suggesting sulphur mineralization, as well as sulphur oxidation, in the release of sulphur ions from APD. We concluded that APD can support microbial growth in vitro and in soils when provided as sole carbon and sulphur source; and that micro-organisms can release sulphur ions from this complex substrate. Microbial release of sulphur ions from APD can account in part for the increased concentrations of sulphur ions in heavy atmospheric-polluted soils.

  10. Microbial release of sulphur ions from atmospheric pollution deposits

    SciTech Connect

    Killham, K.; Wainwright, M.

    1981-12-01

    The surface of leaves of Acer pseudoplatanus growing in areas exposed to heavy atmospheric pollution are covered with atmospheric pollution deposits (APD). Using scanning electric microscopy, micro-organisms were seen to be growing in intimate association with these deposits. The deposits contained sufficient carbon and nitrogen to support growth of the fungus Fusarium solani in culture and in autoclaved and non-sterilized soils; and sufficient reduced sulphur for in vitro growth of Thiobacillus thioparus. When T. thioparus and F. solani were grown in medium supplemented with APD as sole carbon and nitrogen sources, increases in the concentrations of soluble S/sub 2/O/sub 3//sup 2/ btw/sup -/ and; S/sub 4/O/sub 6//sup 2 -/ and SO/sub 4//sup 2 -/ resulted. Similar increases also occurred when APD was added to complete fungal growth medium. Increases in LiCl/sub 2/-extractable sulphur-ions also occurred is fresh soil amended with APD, and in autoclaved soils containing APD, and inoculated with spores of F. solani. Arylsulphatase activity increased in fresh soils and in soils autoclaved and inoculated with F. solani when APD was added; suggesting sulphur mineralization, as well as sulphur oxidation, in the release of sulphur ions from APD. We conclude that APD can support microbial growth in vitro and in soils when provided as sole carbon and sulphur source; and that micro-organisms can release sulphur ions from this complex substrate. Microbial release of sulphur ions from APD can account in part for the increased concentrations of sulphur ions in heavy atmospheric-polluted soils.

  11. In vitro prominent bone regeneration by release zinc ion from Zn-modified implant

    SciTech Connect

    Yusa, Kazuyuki; Yamamoto, Osamu; Fukuda, Masayuki; Koyota, Souichi; Koizumi, Yukio; Sugiyama, Toshihiro

    2011-08-26

    Highlights: {yields} We isolated the Zn{sup 2+} ions (eluted Zn{sup 2+} ion; EZ) from zinc-incorporated titanium implant. {yields} The EZ promoted the cell viability in hBMCs. {yields} The EZ stimulated preosteoblast and osteoblast marker gene expression in hBMCs. {yields} The hBMCs supplemented with EZ showed typically cell morphology when osteoblast maturing. {yields} It is revealed that the EZ also stimulates the calcium deposition of hBMCs. -- Abstract: Zinc is one of the trace elements which induce the proliferation and the differentiation of the osteoblast. In the previous study, we found that zinc ions (Zn{sup 2+} ion)-releasing titanium implants had excellent bone fixation using a rabbit femurs model. In this study, we isolated the Zn{sup 2+} ions (eluted Zn{sup 2+} ion; EZ) released from the implant surface, and evaluated the effect of EZ on the osteogenesis of human bone marrow-derived mesenchymal cells (hBMCs). In the result, it was found that the EZ stimulated cell viability, osteoblast marker gene (type I collagen, osteocalcin (OC), alkaline phosphatase (ALP) and bone sialoprotein (BSP)) expressions and calcium deposition in hBMCs.

  12. Elemental microanalysis in ecophysiology using ion microbeam

    NASA Astrophysics Data System (ADS)

    Przybyłowicz, W. J.; Mesjasz-Przybyłowicz, J.; Migula, P.; Turnau, K.; Nakonieczny, M.; Augustyniak, M.; Głowacka, E.

    2004-06-01

    A few recent applications of elemental microanalysis based on proton beam in ecophysiology and ecotoxicology are shown. They are related to biofiltering capabilities of mycorrhiza (symbiosis between fungi and plant roots) and to plant-insect herbivore interactions. The reported results were obtained at iThemba LABS, South Africa. PIXE and BS techniques were simultaneously used. True elemental maps were generated using a VMS version and PC version of GeoPIXE (GeoPIXE I and II). Further analysis was performed using PIXE and BS spectra extracted from list-mode data and corresponding to specific organs of an insect or a plant.

  13. Ion-release kinetics and ecotoxicity effects of silver nanoparticles.

    PubMed

    Lee, Yong-Ju; Kim, Jiwon; Oh, Jeehyun; Bae, Sujin; Lee, Sungkyu; Hong, In Seok; Kim, Sang-Ho

    2012-01-01

    The environmental toxicity associated with silver nanoparticles (AgNPs) has been a major focus in nanotoxicology. The Ag(+) released from AgNPs may affect ecotoxicity, although whether the major toxic effect is governed by Ag(+) ions or by AgNPs themselves is unclear. In the present study, we have examined the ecotoxicity of AgNPs in aquatic organisms, silver ion-release kinetics of AgNPs, and their relationship. The 48-h median effective concentration (EC50) values for Daphnia magna of powder-type AgNP suspensions were 0.75 µg/L (95% confidence interval [CI] = 0.71-0.78) total Ag and 0.37 µg/L (95% CI = 0.36-0.38) dissolved Ag. For sol-type AgNP suspension, the 48-h EC50 values for D. magna were 7.98 µg/L (95% CI = 7.04-9.03) total Ag and 0.88 µg/L (95% CI = 0.80-0.97) dissolved Ag. The EC50 values for the dissolved Ag of powder-type and sol-type AgNPs for D. magna showed similar results (0.37 µg/L and 0.88 µg/L) despite their differences of EC50 values in total Ag. We observed that the first-order rate constant (k) of Ag(+) ions released from AgNPs was 0.0734/h at 0.05 mg/L total Ag at 22°C within 6 h. The kinetic experiments and the toxicity test showed that 36% and 11% of sol-type AgNPs were converted to the Ag(+) ion form under oxidation conditions, respectively. Powder-type AgNPs showed 49% conversion rate of Ag(+) ion from AgNPs. We also confirmed that Ag(+) ion concentration in AgNP suspension reaches an equilibrium concentration after 48 h, which is an exposure time of the acute aquatic toxicity test.

  14. Silver nanoparticles embedded in zeolite membranes: release of silver ions and mechanism of antibacterial action

    PubMed Central

    Nagy, Amber; Harrison, Alistair; Sabbani, Supriya; Munson, Robert S; Dutta, Prabir K; Waldman, W James

    2011-01-01

    Background The focus of this study is on the antibacterial properties of silver nanoparticles embedded within a zeolite membrane (AgNP-ZM). Methods and Results These membranes were effective in killing Escherichia coli and were bacteriostatic against methicillin-resistant Staphylococcus aureus. E. coli suspended in Luria Bertani (LB) broth and isolated from physical contact with the membrane were also killed. Elemental analysis indicated slow release of Ag+ from the AgNP-ZM into the LB broth. The E. coli killing efficiency of AgNP-ZM was found to decrease with repeated use, and this was correlated with decreased release of silver ions with each use of the support. Gene expression microarrays revealed upregulation of several antioxidant genes as well as genes coding for metal transport, metal reduction, and ATPase pumps in response to silver ions released from AgNP-ZM. Gene expression of iron transporters was reduced, and increased expression of ferrochelatase was observed. In addition, upregulation of multiple antibiotic resistance genes was demonstrated. The expression levels of multicopper oxidase, glutaredoxin, and thioredoxin decreased with each support use, reflecting the lower amounts of Ag+ released from the membrane. The antibacterial mechanism of AgNP-ZM is proposed to be related to the exhaustion of antioxidant capacity. Conclusion These results indicate that AgNP-ZM provide a novel matrix for gradual release of Ag+. PMID:21931480

  15. Calcium and phosphate ion releasing composite: Effect of pH on release and mechanical properties

    PubMed Central

    Xu, Hockin H. K.; Weir, Michael D.; Sun, Limin

    2009-01-01

    Objectives Secondary caries and restoration fracture are the two main challenges facing tooth cavity restorations. The objective of this study was to develop a composite using tetracalcium phosphate (TTCP) fillers and whiskers to be stress-bearing, and to be “smart” to increase the calcium (Ca) and phosphate (PO4) ion release at cariogenic pH. Methods TTCP was ball-milled to obtain four different particle sizes: 16.2 μm, 2.4 μm, 1.3 μm, and 0.97 μm. Whiskers fused with nano-sized silica were combined with TTCP as fillers in a resin. Filler level mass fractions varied from 0% to 75%. Ca and PO4 ion release were measured vs. time at pH of 7.4, 6, and 4. Composite mechanical properties were measured via three-point flexure before and after immersion in solutions at the three pH. Results TTCP composite without whiskers had flexural strength similar to a resin-modified glass ionomer (Vitremer) and previous Ca-PO4 composites. With whiskers, the TTCP composite had a flexural strength (mean ± sd; n = 5) of (116 ± 9) MPa, similar to (112 ± 14) MPa of a stress-bearing, non-releasing hybrid composite (TPH) (p > 0.1). The Ca release was (1.22 ± 0.16) mmol/L at pH of 4, higher than (0.54 ± 0.09) at pH of 6, and (0.22 ± 0.06) at pH of 7.4 (p < 0.05). PO4 release was also dramatically increased at acidic pH. After immersion, the TTCP-whisker composite matched the strength of TPH at all three pH (p > 0.1); both TTCP-whisker composite and TPH had strengths about 3-fold that of a releasing control. Significance The new TTCP-whisker composite was “smart” and increased the Ca and PO4 release dramatically when the pH was reduced from neutral to a cariogenic pH of 4, when these ions are most needed to inhibit caries. Its strength was 2–3 fold higher than previously-known Ca-PO4 composites and resin-modified glass ionomer. This composite may have the potential to provide the necessary combination of load-bearing and caries-inhibiting capabilities. PMID:19101026

  16. Energy Release, Acceleration, and Escape of Solar Energetic Ions

    NASA Astrophysics Data System (ADS)

    de Nolfo, G. A.; Ireland, J.; Ryan, J. M.; Young, C. A.

    2013-12-01

    Solar flares are prodigious producers of energetic particles, and thus a rich laboratory for studying particle acceleration. The acceleration occurs through the release of magnetic energy, a significant fraction of which can go into the acceleration of particles. Coronal mass ejections (CMEs) certainly produce shocks that both accelerate particles and provide a mechanism for escape into the interplanetary medium (IP). What is less well understood is whether accelerated particles produced from the flare reconnection process escape, and if so, how these same particles are related to solar energetic particles (SEPs) detected in-situ. Energetic electron SEPs have been shown to be correlated with Type III radio bursts, hard X-ray emission, and EUV jets, making a very strong case for the connection between acceleration at the flare and escape along open magnetic field lines. Because there has not been a clear signature of ion escape, as is the case with the Type III radio emission for electrons, sorting out the avenues of escape for accelerated flare ions and the possible origin of the impulsive SEPs continues to be a major challenge. The key to building a clear picture of particle escape relies on the ability to map signatures of escape such as EUV jets at the Sun and to follow the progression of these escape signatures as they evolve in time. Furthermore, nuclear γ-ray emissions provide critical context relating ion acceleration to that of escape. With the advent observations from Fermi as well as RHESSI and the Solar Dynamics Observatory (SDO), the challenge of ion escape from the Sun can now be addressed. We present a preliminary study of the relationship of EUV jets with nuclear γ-ray emission and Type III radio observations and discuss the implications for possible magnetic topologies that allow for ion escape from deep inside the corona to the interplanetary medium.

  17. The effect of platform switching on the levels of metal ion release from different implant–abutment couples

    PubMed Central

    Alrabeah, Ghada O; Knowles, Jonathan C; Petridis, Haralampos

    2016-01-01

    The improved peri-implant bone response demonstrated by platform switching may be the result of reduced amounts of metal ions released to the surrounding tissues. The aim of this study was to compare the levels of metal ions released from platform-matched and platform-switched implant–abutment couples as a result of accelerated corrosion. Thirty-six titanium alloy (Ti-6Al-4V) and cobalt–chrome alloy abutments were coupled with titanium cylinders forming either platform-switched or platform-matched groups (n=6). In addition, 18 unconnected samples served as controls. The specimens were subjected to accelerated corrosion by static immersion in 1% lactic acid for 1 week. The amount of metal ions ion of each test tube was measured using inductively coupled plasma mass spectrometry. Scanning electron microscope (SEM) images and energy dispersive spectroscopy X-ray analyses were performed pre- and post-immersion to assess corrosion at the interface. The platform-matched groups demonstrated higher ion release for vanadium, aluminium, cobalt, chrome, and molybdenum compared with the platform-switched groups (P<0.05). Titanium was the highest element to be released regardless of abutment size or connection (P<0.05). SEM images showed pitting corrosion prominent on the outer borders of the implant and abutment platform surfaces. In conclusion, implant–abutment couples underwent an active corrosion process resulting in metal ions release into the surrounding environment. The highest amount of metal ions released was recorded for the platform-matched groups, suggesting that platform-switching concept has a positive effect in reducing the levels of metal ion release from the implant–abutment couples. PMID:27357323

  18. Molecular ion battery: a rechargeable system without using any elemental ions as a charge carrier.

    PubMed

    Yao, Masaru; Sano, Hikaru; Ando, Hisanori; Kiyobayashi, Tetsu

    2015-06-04

    Is it possible to exceed the lithium redox potential in electrochemical systems? It seems impossible to exceed the lithium potential because the redox potential of the elemental lithium is the lowest among all the elements, which contributes to the high voltage characteristics of the widely used lithium ion battery. However, it should be possible when we use a molecule-based ion which is not reduced even at the lithium potential in principle. Here we propose a new model system using a molecular electrolyte salt with polymer-based active materials in order to verify whether a molecular ion species serves as a charge carrier. Although the potential of the negative-electrode is not yet lower than that of lithium at present, this study reveals that a molecular ion can work as a charge carrier in a battery and the system is certainly a molecular ion-based "rocking chair" type battery.

  19. Molecular ion battery: a rechargeable system without using any elemental ions as a charge carrier

    PubMed Central

    Yao, Masaru; Sano, Hikaru; Ando, Hisanori; Kiyobayashi, Tetsu

    2015-01-01

    Is it possible to exceed the lithium redox potential in electrochemical systems? It seems impossible to exceed the lithium potential because the redox potential of the elemental lithium is the lowest among all the elements, which contributes to the high voltage characteristics of the widely used lithium ion battery. However, it should be possible when we use a molecule-based ion which is not reduced even at the lithium potential in principle. Here we propose a new model system using a molecular electrolyte salt with polymer-based active materials in order to verify whether a molecular ion species serves as a charge carrier. Although the potential of the negative-electrode is not yet lower than that of lithium at present, this study reveals that a molecular ion can work as a charge carrier in a battery and the system is certainly a molecular ion-based “rocking chair” type battery. PMID:26043147

  20. Automated identification of elemental ions in macromolecular crystal structures

    SciTech Connect

    Echols, Nathaniel Morshed, Nader; Afonine, Pavel V.; McCoy, Airlie J.; Read, Randy J.; Terwilliger, Thomas C.; Adams, Paul D.

    2014-04-01

    The solvent-picking procedure in phenix.refine has been extended and combined with Phaser anomalous substructure completion and analysis of coordination geometry to identify and place elemental ions. Many macromolecular model-building and refinement programs can automatically place solvent atoms in electron density at moderate-to-high resolution. This process frequently builds water molecules in place of elemental ions, the identification of which must be performed manually. The solvent-picking algorithms in phenix.refine have been extended to build common ions based on an analysis of the chemical environment as well as physical properties such as occupancy, B factor and anomalous scattering. The method is most effective for heavier elements such as calcium and zinc, for which a majority of sites can be placed with few false positives in a diverse test set of structures. At atomic resolution, it is observed that it can also be possible to identify tightly bound sodium and magnesium ions. A number of challenges that contribute to the difficulty of completely automating the process of structure completion are discussed.

  1. Rocket having barium release system to create ion clouds in the upper atmosphere

    NASA Technical Reports Server (NTRS)

    Lewis, B. W.; Stokes, C. S.; Smith, E. W.; Murphy, W. J. (Inventor)

    1974-01-01

    A chemical system for releasing a good yield of free barium atoms and barium ions to create ion clouds in the upper atmosphere and interplanetary space for the study of the geophysical properties of the medium is presented.

  2. Multi-element logic gates for trapped-ion qubits

    NASA Astrophysics Data System (ADS)

    Tan, T. R.; Gaebler, J. P.; Lin, Y.; Wan, Y.; Bowler, R.; Leibfried, D.; Wineland, D. J.

    2015-12-01

    Precision control over hybrid physical systems at the quantum level is important for the realization of many quantum-based technologies. In the field of quantum information processing (QIP) and quantum networking, various proposals discuss the possibility of hybrid architectures where specific tasks are delegated to the most suitable subsystem. For example, in quantum networks, it may be advantageous to transfer information from a subsystem that has good memory properties to another subsystem that is more efficient at transporting information between nodes in the network. For trapped ions, a hybrid system formed of different species introduces extra degrees of freedom that can be exploited to expand and refine the control of the system. Ions of different elements have previously been used in QIP experiments for sympathetic cooling, creation of entanglement through dissipation, and quantum non-demolition measurement of one species with another. Here we demonstrate an entangling quantum gate between ions of different elements which can serve as an important building block of QIP, quantum networking, precision spectroscopy, metrology, and quantum simulation. A geometric phase gate between a 9Be+ ion and a 25Mg+ ion is realized through an effective spin-spin interaction generated by state-dependent forces induced with laser beams. Combined with single-qubit gates and same-species entangling gates, this mixed-element entangling gate provides a complete set of gates over such a hybrid system for universal QIP. Using a sequence of such gates, we demonstrate a CNOT (controlled-NOT) gate and a SWAP gate. We further demonstrate the robustness of these gates against thermal excitation and show improved detection in quantum logic spectroscopy. We also observe a strong violation of a CHSH (Clauser-Horne-Shimony-Holt)-type Bell inequality on entangled states composed of different ion species.

  3. Influence of Finite Element Software on Energy Release Rates Computed Using the Virtual Crack Closure Technique

    NASA Technical Reports Server (NTRS)

    Krueger, Ronald; Goetze, Dirk; Ransom, Jonathon (Technical Monitor)

    2006-01-01

    Strain energy release rates were computed along straight delamination fronts of Double Cantilever Beam, End-Notched Flexure and Single Leg Bending specimens using the Virtual Crack Closure Technique (VCCT). Th e results were based on finite element analyses using ABAQUS# and ANSYS# and were calculated from the finite element results using the same post-processing routine to assure a consistent procedure. Mixed-mode strain energy release rates obtained from post-processing finite elem ent results were in good agreement for all element types used and all specimens modeled. Compared to previous studies, the models made of s olid twenty-node hexahedral elements and solid eight-node incompatible mode elements yielded excellent results. For both codes, models made of standard brick elements and elements with reduced integration did not correctly capture the distribution of the energy release rate acr oss the width of the specimens for the models chosen. The results suggested that element types with similar formulation yield matching results independent of the finite element software used. For comparison, m ixed-mode strain energy release rates were also calculated within ABAQUS#/Standard using the VCCT for ABAQUS# add on. For all specimens mod eled, mixed-mode strain energy release rates obtained from ABAQUS# finite element results using post-processing were almost identical to re sults calculated using the VCCT for ABAQUS# add on.

  4. A parallel finite element simulator for ion transport through three-dimensional ion channel systems.

    PubMed

    Tu, Bin; Chen, Minxin; Xie, Yan; Zhang, Linbo; Eisenberg, Bob; Lu, Benzhuo

    2013-09-15

    A parallel finite element simulator, ichannel, is developed for ion transport through three-dimensional ion channel systems that consist of protein and membrane. The coordinates of heavy atoms of the protein are taken from the Protein Data Bank and the membrane is represented as a slab. The simulator contains two components: a parallel adaptive finite element solver for a set of Poisson-Nernst-Planck (PNP) equations that describe the electrodiffusion process of ion transport, and a mesh generation tool chain for ion channel systems, which is an essential component for the finite element computations. The finite element method has advantages in modeling irregular geometries and complex boundary conditions. We have built a tool chain to get the surface and volume mesh for ion channel systems, which consists of a set of mesh generation tools. The adaptive finite element solver in our simulator is implemented using the parallel adaptive finite element package Parallel Hierarchical Grid (PHG) developed by one of the authors, which provides the capability of doing large scale parallel computations with high parallel efficiency and the flexibility of choosing high order elements to achieve high order accuracy. The simulator is applied to a real transmembrane protein, the gramicidin A (gA) channel protein, to calculate the electrostatic potential, ion concentrations and I - V curve, with which both primitive and transformed PNP equations are studied and their numerical performances are compared. To further validate the method, we also apply the simulator to two other ion channel systems, the voltage dependent anion channel (VDAC) and α-Hemolysin (α-HL). The simulation results agree well with Brownian dynamics (BD) simulation results and experimental results. Moreover, because ionic finite size effects can be included in PNP model now, we also perform simulations using a size-modified PNP (SMPNP) model on VDAC and α-HL. It is shown that the size effects in SMPNP can

  5. Reduction of Cupric Ions with Elemental Sulfur by Thiobacillus ferrooxidans.

    PubMed

    Sugio, T; Tsujita, Y; Inagaki, K; Tano, T

    1990-03-01

    In anaerobic or aerobic conditions in the presence of 5 mM sodium cyanide, an inhibitor of iron oxidase, cupric ion (Cu) was reduced enzymatically with elemental sulfur (S) by washed intact cells of Thiobacillus ferrooxidans AP19-3 to give cuprous ion (Cu). The rate of Cu reduction was proportional to the concentrations of S and Cu added to the reaction mixture. The pH optimum for the cupric ion-reducing system was 5.0, and the activity was completely destroyed by 10-min incubation of cells at 70 degrees C. The activity of Cu reduction with S by this strain was strongly inhibited by inhibitors of hydrogen sulfide: ferric ion oxidoreductase (SFORase), such as alpha,alpha'-dipyridyl, 4,5-dihydroxy-m-benzene disulfonic acid disodium salts, and diazine dicarboxylic acid bis-(N, N-dimethylamide). A SFORase purified from this strain, which catalyzes oxidation of both hydrogen sulfide and S with Fe or Mo as an electron acceptor in the presence of glutathione, catalyzed a reduction of Cu by S, and the Michaelis constant of SFORase for Cu was 7.2 mM, indicating that a SFORase catalyzes the reduction of not only Fe and Mo but also Cu.

  6. Reduction of Cupric Ions with Elemental Sulfur by Thiobacillus ferrooxidans

    PubMed Central

    Sugio, Tsuyoshi; Tsujita, Yoshihiko; Inagaki, Kenji; Tano, Tatsuo

    1990-01-01

    In anaerobic or aerobic conditions in the presence of 5 mM sodium cyanide, an inhibitor of iron oxidase, cupric ion (Cu2+) was reduced enzymatically with elemental sulfur (S0) by washed intact cells of Thiobacillus ferrooxidans AP19-3 to give cuprous ion (Cu+). The rate of Cu2+ reduction was proportional to the concentrations of S0 and Cu2+ added to the reaction mixture. The pH optimum for the cupric ion-reducing system was 5.0, and the activity was completely destroyed by 10-min incubation of cells at 70°C. The activity of Cu2+ reduction with S0 by this strain was strongly inhibited by inhibitors of hydrogen sulfide: ferric ion oxidoreductase (SFORase), such as α,α′-dipyridyl, 4,5-dihydroxy-m-benzene disulfonic acid disodium salts, and diazine dicarboxylic acid bis-(N, N-dimethylamide). A SFORase purified from this strain, which catalyzes oxidation of both hydrogen sulfide and S0 with Fe3+ or Mo6+ as an electron acceptor in the presence of glutathione, catalyzed a reduction of Cu2+ by S0, and the Michaelis constant of SFORase for Cu2+ was 7.2 mM, indicating that a SFORase catalyzes the reduction of not only Fe3+ and Mo6+ but also Cu2+. PMID:16348143

  7. Reactive-element effect studied using ion implantation

    SciTech Connect

    King, W.E.; Grabowski, K.S.

    1988-11-01

    Implantation of reactive elements into metals that form chromia layers upon exposure to high temperature oxidizing environments has a very large effect on the growth rate of the oxide and adhesion of the oxide to the base alloy. We have investigated the effect of Y ion implantation on the high temperature oxidation of Fe-24Cr using Rutherford backscattering spectroscopy, secondary ion mass spectroscopy, and electron microscopy. Analytical tools have been applied to determine the spatial distribution of Y, the microstructure of the oxide, and contribution of oxygen transport to the oxidation process. Results are compared with similar experiments in Fe-Cr alloys with Y additions and with results of cation and anion tracer diffusion experiments. 51 refs., 17 figs., 3 tabs.

  8. Controls on Fe(II)-Activated Trace Element Release from Goethite and Hematite

    SciTech Connect

    Frierdich, Andrew J.; Catalano, Jeffrey G.

    2012-03-26

    Electron transfer and atom exchange (ETAE) between aqueous Fe(II) and Fe(III) oxides induces surface growth and dissolution that affects trace element fate and transport. We have recently demonstrated Ni(II) cycling through goethite and hematite (adsorbed Ni incorporates into the mineral structure and preincorporated Ni releases to solution) during Fe(II)-Fe(III) ETAE. However, the chemical parameters affecting net trace element release remain unknown. Here, we examine the chemical controls on Ni(II) and Zn(II) release from Ni- and Zn-substituted goethite and hematite during reaction with Fe(II). Release follows a rate law consistent with surface reaction limited mineral dissolution and suggests that release occurs near sites of Fe(III) reductive dissolution during Fe(II)-Fe(III) ETAE. Metal substituent type affects reactivity; Zn release is more pronounced from hematite than goethite, whereas the opposite trend occurs for Ni. Buildup of Ni or Zn in solution inhibits further release but this resumes upon fluid exchange, suggesting that sustained release is possible under flow conditions. Mineral and aqueous Fe(II) concentrations as well as pH strongly affect sorbed Fe(II) concentrations, which directly control the reaction rates and final metal concentrations. Our results demonstrate that structurally incorporated trace elements are mobilized from iron oxides into fluids without abiotic or microbial net iron reduction. Such release may affect micronutrient availability, contaminant transport, and the distribution of redox-inactive trace elements in natural and engineered systems.

  9. Effect of alloy surface composition on release of elements from dental casting alloys.

    PubMed

    Wataha, J C; Malcolm, C T

    1996-09-01

    The release of elements from dental casting alloys is a continuing concern because of the potentially harmful biological effects the elements may have on local tissues. The surfaces of the alloys appear to be most important in controlling the release of these elements. In the current study, the surfaces of high-, reduced-, and no-gold dental alloys were analysed by X-ray photoelectron spectroscopy before and after they were exposed to a biological medium for up to 96 h. The goal was to relate the release of elements from these alloys to their surface composition, and to determine the depth of the effect of the medium. The depth of the effect of the exposure was determined by argon milling of the alloy surface after exposure to the medium. Elements that were released into the medium were measured by means of atomic absorption spectroscopy. The release of elements from alloys was greater when the atomic ratio of noble to non-noble elements at the surface was less than 1. The depth of the effect of the medium varied with the alloy, but was always less than 100 A. The surface composition was significantly different from layers only 5 A below. It was concluded that the surface concentration of noble elements is important in controlling the release of non-noble elements from these alloys, and the surface composition appeared to be only one or two atomic layers thick. Of the three types of alloys, the high-gold alloy appeared to develop the most stable surface composition which released the lowest levels of elements.

  10. Dual Ion Beam Deposition Of Diamond Films On Optical Elements

    NASA Astrophysics Data System (ADS)

    Deutchman, Arnold H.; Partyka, Robert J.; Lewis, J. C.

    1990-01-01

    Diamond film deposition processes are of great interest because of their potential use for the formation of both protective as well as anti-reflective coatings on the surfaces of optical elements. Conventional plasma-assisted chemical vapor deposition diamond coating processes are not ideal for use on optical components because of the high processing temperatures required, and difficulties faced in nucleating films on most optical substrate materials. A unique dual ion beam deposition technique has been developed which now makes possible deposition of diamond films on a wide variety of optical elements. The new DIOND process operates at temperatures below 150 aegrees Farenheit, and has been used to nucleate and grow both diamondlike carbon and diamond films on a wide variety of optical :taterials including borosilicate glass, quartz glass, plastic, ZnS, ZnSe, Si, and Ge.

  11. Large areas elemental mapping by ion beam analysis techniques

    NASA Astrophysics Data System (ADS)

    Silva, T. F.; Rodrigues, C. L.; Curado, J. F.; Allegro, P.; Moro, M. V.; Campos, P. H. O. V.; Santos, S. B.; Kajiya, E. A. M.; Rizzutto, M. A.; Added, N.; Tabacniks, M. H.

    2015-07-01

    The external beam line of the Laboratory for Material Analysis with Ion Beams (LAMFI) is a versatile setup for multi-technique analysis. X-ray detectors for Particle Induced X-rays Emission (PIXE) measurements, a Gamma-ray detector for Particle Induced Gamma- ray Emission (PIGE), and a particle detector for scattering analysis, such as Rutherford Backscattering Spectrometry (RBS), were already installed. In this work, we present some results, using a large (60-cm range) XYZ computer controlled sample positioning system, completely developed and build in our laboratory. The XYZ stage was installed at the external beam line and its high spacial resolution (better than 5 μm over the full range) enables positioning the sample with high accuracy and high reproducibility. The combination of a sub-millimeter beam with the large range XYZ robotic stage is being used to produce elemental maps of large areas in samples like paintings, ceramics, stones, fossils, and all sort of samples. Due to its particular characteristics, this is a unique device in the sense of multi-technique analysis of large areas. With the continuous development of the external beam line at LAMFI, coupled to the robotic XYZ stage, it is becoming a robust and reliable option for regular analysis of trace elements (Z > 5) competing with the traditional in-vacuum ion-beam-analysis with the advantage of automatic rastering.

  12. In vitro corrosion behaviour and metallic ion release of different prosthodontic alloys.

    PubMed

    Gil, F J; Sánchez, L A; Espías, A; Planell, J A

    1999-12-01

    The corrosion resistance for six metallic alloys often used in clinical dentistry, was evaluated by measuring their polarisation resistance in an artificial saliva environment. The critical current density (icr), the passive current density (ip), the corrosion potential (Ecorr) and the critical pitting potential (Ecp), were studied. Metallic ion release from the different alloys was analysed in a saliva environment at 37 degrees C. The nickel-chromium alloy exhibited important corrosion and a high quantity of ions was released. The titanium presented a low value of ion release and a good corrosion resistance due to the passive film on the metal surface. The high gold content alloy provided the best corrosion resistance.

  13. The Release of Elements from Dental Casting Alloy into Cell-Culture Medium and Artificial Saliva

    PubMed Central

    Can, Gülşen; Akpınar, Gül; Aydın, Ahmet

    2007-01-01

    Objectives The biocompatibility of dental casting alloys is a critical issue because these alloys are in long-term intimate contact with oral tissues. Since the biocompatibility of alloys is not completely known; the release of elements from the alloys has been studied. The aim of this study was to compare the elemental release from dental casting alloy during exposure to artificial saliva and cell-culture medium. Materials and Methods Twenty specimens made from Ni-Cr alloy were provided in the form of 5 mm diameter discs, 2 mm in thickness with a 7 mm stem attached to one face to facilitate handling. Ten of twenty samples were polished separately using a conventional technique. The remaining ten samples were left sandblasted with 50 μm Al203. Ten samples (5 polished, 5 sandblasted) were separately placed into cell-culture wells with Dulbecco’s Modified Eagle’s Medium. The other ten samples were placed separately into cell-culture wells with artificial saliva. The samples were subjected in contact with these medium for 30 days. These medium were collected every 7 days. The cell-culture medium and artificial saliva without alloy samples were subjected to elemental analyses as a control. At the end of the exposure time, Atomic Absorption Spectrometry (AAS) was used to determine the release of elements from the alloys into all collected medium. Statistical analyses were assessed with two-way ANOVA. Results In general, the elemental release occurred with in all medium. The elemental releases of sandblasted alloys were higher than polished alloys. Artificial saliva was found to cause more release from the samples. In both media, Ni released from polished and sandblasted alloys were higher than Cr and Mo. Conlusions The results suggest that the release of elements from the alloys might have correlated with the environments and the surface of dental alloy. PMID:19212482

  14. An experimental study on major element release from the sediments in the Changjiang (Yangtze River) Estuary

    NASA Astrophysics Data System (ADS)

    Guo, Yanwei; Yang, Shouye

    2015-06-01

    With the enhanced warming and acidification of global ocean, whether and to what extent the naturally-weathered fluvial sediment into the sea can release elements and thus influence the geochemical process and ecosystem of global ocean remain to be resolved. In this contribution, an experimental study was carried out to examine the release rates of major elements (Ca, K, Mg and Al) from the surface sediments in the Changjiang (Yangtze River) Estuary under the pH values of 4.0, 6.0 and 7.0. The two studied sediments consist primarily of quartz, plagioclase, calcite and clay minerals, with the BET (Brunauer, Emmett and Teller) surface areas of 61.7 m2 g-1 and 23.1 m2 g-1. Major elements of Ca, K, Mg and Al show different release rates under different solution pH values. With the decreasing solution pH, the release rates of Ca and K increase obviously, while the release rates of Mg and Al increase with the initial solution pH varying from 6.0 to 7.0. The different release rates of these elements are closely related to the original mineral composition of the sediments and the reaction kinetics. Based on the experimental observation, quartz and clay minerals that have low dissolution rates may dominate the major element release to the aqueous phase. This study reveals that the enhancing ocean acidification could cause considerable release of major elements from natural terrigenous sediments into the ambient marine environment, which has to be considered carefully in the future study on global change.

  15. Rechargeable dental adhesive with calcium phosphate nanoparticles for long-term ion release

    PubMed Central

    Zhang, Ling; Weir, Michael D.; Hack, Gary; Fouad, Ashraf F.; Xu, Hockin H. K.

    2015-01-01

    Objectives The tooth-resin bond is the weak link of restoration, with secondary caries as a main reason for failure. Calcium phosphate-containing resins are promising for remineralization; however, calcium (Ca) and phosphate (P) ion releases last only a couple of months. The objectives of this study were to develop the first rechargeable CaP bonding agent and investigate the key factors that determine CaP ion recharge and re-release. Methods Nanoparticles of amorphous calcium phosphate (NACP) were synthesized. Pyromellitic glycerol dimethacrylate (PMGDM), ethoxylated bisphenol-A dimethacrylate (EBPADMA), 2-hydroxyethyl methacrylate (HEMA), and bisphenol-A glycidyl dimethacrylate (BisGMA) were used to synthesize three adhesives (denoted PE, PEH and PEHB). NACP were mixed into adhesive at 0–30% by mass. Dentin shear bond strengths were measured. Adhesive specimens were tested for Ca and P initial ion release. Then the ion-exhausted specimens were immersed in Ca and P solution to recharge the specimens, and the recharged specimens were then used to measure ion re-release for 7 days as one cycle. Then these specimens were again recharged and the re-release was measured for 7 days as the second cycle. Three recharge/re-release cycles were tested. Results PEHB had the highest dentin bond strength (p<0.05). Increasing NACP content from 0 to 30% did not affect dentin bond strength (p>0.1), but increased CaP release and re-release (p<0.05). PEHB-NACP had the greatest recharge/re-release, and PE-NACP had the least (p<0.05). Ion release remained high and did not decrease with increasing the number of recharge/re-release cycles (p>0.1). After the third cycle, specimens without further recharge had continuous CaP ion release for 2–3 weeks. Significance Rechargeable CaP bonding agents were developed for the first time to provide long-term Ca and P ions to promote remineralization and reduce caries. Incorporation of NACP into adhesive had no negative effect on dentin bond

  16. Tracing nuclear elements released by Fukushima Nuclear Power Plant accident

    NASA Astrophysics Data System (ADS)

    Tsujimura, M.; Onda, Y.; Abe, Y.; Hada, M.; Pun, I.

    2011-12-01

    Radioactive contamination has been detected in Fukushima and the neighboring regions due to the nuclear accident at Fukushima Daiichi Nuclear Power Plant (NPP) following the earthquake and tsunami occurred on 11th March 2011. The small experimental catchments have been established in Yamakiya district, Kawamata Town, Fukushima Prefecture, located approximately 35 km west from the Fukushima NPP. The tritium (3H) concentration and stable isotopic compositions of deuterium and oxygen-18 have been determined on the water samples of precipitation, soil water at the depths of 10 to 30 cm, groundwater at the depths of 5 m to 50 m, spring water and stream water taken at the watersheds in the recharge and discharge zones from the view point of the groundwater flow system. The tritium concentration of the rain water fell just a few days after the earthquake showed a value of approximately 17 Tritium Unit (T.U.), whereas the average concentration of the tritium in the precipitation was less than 5 T.U. before the Fukushima accident. The spring water in the recharge zone showed a relatively high tritium concentration of approximately 12 T.U., whereas that of the discharge zone showed less than 5 T.U. Thus, the artificial tritium was apparently injected in the groundwater flow system due to the Fukushima NPP accident, whereas that has not reached at the discharge zone yet. The monitoring of the nuclear elements is now on going from the view points of the hydrological cycles and the drinking water security.

  17. Potentially toxic element release by fenton oxidation of sewage sludge.

    PubMed

    Andrews, J P; Asaadi, M; Clarke, B; Ouki, S

    2006-01-01

    The presence, in sewage sludge, of excess levels of the potentially toxic elements (PTE) copper, zinc, chromium, cadmium, nickel, lead and mercury, could impact on our ability to recycle these residues in the future. Far stricter limits on the levels of PTEs are likely in proposed legislation. A method involving the dosing of Fenton's reagent, a mixture of ferrous iron and hydrogen peroxide, under acidic conditions was evaluated for its potential to reduce metal levels. The [Fe]:[H2O2] (w/w) ratio was found to give a good indication of the percentage copper and zinc elution obtainable. Sites with no iron dosing as part of wastewater treatment required extra iron to be added in order to initiate the Fenton's reaction. A significant reduction, in excess of 70%, of the copper and zinc was eluted from both raw primary and activated sludge solid fractions. Cadmium and nickel could be reduced to below detection limits but elution of mercury, lead and chromium was less than 40%. The iron catalyst concentration was found to be a crucial parameter. This process has the potential to reduce the heavy metal content of the sludge and allow the recycling of sludge to continue in a sustainable manner.

  18. Tramadol loading, release and iontophoretic characteristics of ion-exchange fiber.

    PubMed

    Gao, Yanan; Yuan, Jing; Liu, Hongzhuo; Yang, Yang; Hou, Yanlong; Li, Sanming

    2014-04-25

    The objective of this study was to investigate the drug loading, release and iontophoretic characteristics of strong acidic ion-exchange fiber, using tramadol hydrochloride as a model drug. The complex of charged model drug and ion-exchange fiber was studied as a new approach to achieve controlled drug delivery. Structural characterization of the fiber was elucidated through different approaches including differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), scanning electron microscope (SEM) and infrared spectroscopy (IR). And the mechanism of drug binding into ion-exchange fibers was validated to be ion-exchange. The drug loading into and release from ion-exchange fiber were affected by the concentration, volume and valence of the counter-ions in the external solution. Iontophoresis could significantly increase the delivery rate and amount of transdermal drug, and the iontophoretic dose could be easily controlled by adjusting the current intensity and the amount of release medium. The tramadol could be steadily released both from the drug-loaded fiber and drug solution when applied the iontophoretic method, which was in disagreement with the previous publications. As a drug reservoir, ion-exchange fiber has good regularity of drug loading, release and iontophoretic characteristics.

  19. Study of Nickel Ion Release in Simulated Body Fluid from C+-IMPLANTED Nickel Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Shafique, Muhammad Ahsan; Murtaza, G.; Saadat, Shahzad; Zaheer, Zeeshan; Shahnawaz, Muhammad; Uddin, Muhammad K. H.; Ahmad, Riaz

    2016-05-01

    Nickel ion release from NiTi shape memory alloy is an issue for biomedical applications. This study was planned to study the effect of C+ implantation on nickel ion release and affinity of calcium phosphate precipitation on NiTi alloy. Four annealed samples are chosen for the present study; three samples with oxidation layer and the fourth without oxidation layer. X-ray diffraction (XRD) spectra reveal amorphization with ion implantation. Proton-induced X-ray emission (PIXE) result shows insignificant increase in Ni release in simulated body fluid (SBF) and calcium phosphate precipitation up to 8×1013ions/cm2. Then Nickel contents show a sharp increase for greater ion doses. Corrosion potential decreases by increasing the dose but all the samples passivate after the same interval of time and at the same level of VSCE in ringer lactate solution. Hardness of samples initially increases at greater rate (up to 8×1013ions/cm2) and then increases with lesser rate. It is found that 8×1013ions/cm2 (≈1014) is a safer limit of implantation on NiTi alloy, this limit gives us lesser ion release, better hardness and reasonable hydroxyapatite incubation affinity.

  20. Inductively coupled plasma mass spectrometer with laser ablation metal ions release detection in the human mouth

    NASA Astrophysics Data System (ADS)

    Kueerova, Hana; Dostalova, Tatjana; Prochazkova, J.

    2002-06-01

    Presence of more dental alloys in oral cavity often causes pathological symptoms. Due to various and multi-faced symptomatology, they tend to be a source of significant problems not only for the patient but also for the dentist. Metal ions released from alloys can cause subjective and objective symptoms in mouth. The aim of this study was detection of metal elements presence in saliva. There were 4 groups of examined persons: with intact teeth (15 individuals) with metallic restorations, pathological currents 5-30 (mu) A, multi-faced subjective symptomatology and uncharacteristic objective diagnosis (32 patients), with metallic restorations and no subjective symptoms (14 persons) and with metallic restorations, without pathological currents and with problems related to galvanism (13 patients). Presence of 14 metal elements was checked by inductively coupled plasma mass spectrometer with laser ablation. Nd:YAG laser detector was used. There were significant differences in content of silver, gold and mercury between persons with intact teeth and other three groups. There were no differences found between subjects with and without galvanic currents, and presence of subjective and objective symptoms.

  1. Development of novel thermal sprayed antibacterial coating and evaluation of release properties of silver ions.

    PubMed

    Noda, Iwao; Miyaji, Fumiaki; Ando, Yoshiki; Miyamoto, Hiroshi; Shimazaki, Takafumi; Yonekura, Yutaka; Miyazaki, Masaki; Mawatari, Masaaki; Hotokebuchi, Takao

    2009-05-01

    Several studies have addressed the use of antibacterial coating to reduce implant-associated infections. In this study, novel silver (Ag)-containing calcium-phosphate (CP) coating technology based on the thermal spraying method was developed. The coating's physical and chemical properties, in vitro antibacterial activity, hydroxyapatite (HA)-forming ability, and release of Ag ions were evaluated. An amorphous structure of the coating was confirmed by X-ray diffraction, and Ag residue in the coating was determined by elementary analysis. The coating showed strong antibacterial activity to methicillin-resistant Staphylococcus aureus in fetal bovine serum (FBS) along with HA-forming ability in simulated body fluid. Therefore, it is expected that the coating would confer antibacterial and bone bonding abilities to the implant surface. Time course release testing of Ag ions from the coating on immersion in FBS showed pronounced Ag release for up to 24 h after immersion, with consistent strong antibacterial activity at the early postoperative stage. In repeated testing, the amount of released Ag ions was about 6500 parts per billion (ppb, microg/L) for the first release test, after which it gradually decreased. However, retention of significant release of Ag ions after a sixth repeat implies that Ag release from the coating is slow in FBS.

  2. On-demand release of corrosion-inhibiting ions from amorphous Al-Co-Ce alloys.

    PubMed

    Jakab, M A; Scully, J R

    2005-09-01

    Controlled release technologies are often used to supply chemicals or drugs at given rates. Release often occurs on contact with solution. However, some applications, such as corrosion protection, require containment of the active species in a reservoir and their slow release when needed. Conductive polymers have been used as reservoirs for corrosion inhibitors whose triggered release occurs by galvanic reduction or ion exchange. This work shows one of the first examples of pH-controlled release of corrosion-inhibiting ions from an amorphous metallic coating where the pH change that triggers release is a consequence of the onset of corrosion. This corrosion-inhibition strategy provides further corrosion protection beyond the traditional roles of barrier and sacrificial cathodic protection using a metal coating. For instance, zinc galvanizing provides sacrificial cathodic protection and acts as a barrier, but does not supply inhibitor ions. In the coating described here, protection of an underlying structural alloy exposed at coating defects is demonstrated by inhibitor ion release in addition to barrier function and sacrificial cathodic protection.

  3. Osmotic effects on vacuolar ion release in guard cells.

    PubMed

    MacRobbie, Enid A C

    2006-01-24

    Tracer flux experiments in isolated guard cells of Commelina communis L. suggest that the vacuolar ion content is regulated and is reset to a reduced fixed point by abscisic acid (ABA) with no significant change in cytoplasmic content. The effects of changes in external osmotic pressure were investigated by adding and removing mannitol from the bathing solution. Two effects were distinguished. In the new steady state of volume and turgor, the vacuolar ion efflux was sensitive to turgor: efflux increased at high turgor and reduced at lower turgor after the addition of mannitol. These changes were inhibited by phenylarsine oxide and are likely to involve the same channel that is involved in the response to ABA. After a hypoosmotic transfer, there was an additional effect: a fast transient stimulation of vacuolar efflux during the period of water flow into the cell; the size of this hypopeak increased with the size of the hypoosmotic shock, with increased water flow. No corresponding transient in reduced vacuolar efflux was observed upon hyperosmotic transfer. The fast hypopeak was not inhibited by phenylarsine oxide and appears to involve a different ion channel from that involved in the resting efflux, the response to ABA, or the turgor sensitivity. Thus, the tonoplast can sense an osmotic gradient and respond to water flow into the vacuole by increased vacuolar ion efflux, thereby minimizing cytoplasmic dilution. An aquaporin is the most likely sensor and may also be involved in the signal transduction chain.

  4. Trace element mapping in Parkinsonian brain by quantitative ion beam microscopy

    NASA Astrophysics Data System (ADS)

    Barapatre, Nirav; Morawski, Markus; Butz, Tilman; Reinert, Tilo

    2010-06-01

    The role of iron in the pathogenesis of the Parkinson's disease (PD) is a current subject of research in Neurochemistry, since an abnormal increase in iron is reported in the substantia nigra (SN) of Parkinsonian patients. A severe loss of the cells containing dopamine in the SN in the PD has also drawn attention towards the function of a browny-black pigment called neuromelanin, which accumulates predominantly in these dopaminergic neurons. The neuromelanin has an ability to chelate metal ions, which, in free state, may cause considerable damage to cells by reacting with their lipid-rich membranes. However, it could also potentiate free radical production if it releases the bound metal ions. The highly sensitive and non-destructive micro-PIXE method suits best to quantify and map the trace elements in the SN. The accuracy in charge measurement for such microanalysis studies is of utmost importance for quantitative analysis. Since a Faraday cup is usually placed behind the thin biological sample to measure the charge, the primary and the secondary electrons, knocked out from the sample by traversing ion beam, hamper an exact charge determination. Hence, a new non-interceptive technique was developed for precise charge measurement and for continuous monitoring of beam current.

  5. Collective capture of released lithium ions in the solar wind

    NASA Technical Reports Server (NTRS)

    Winske, D.; Wu, C. S.; Li, Y. Y.; Zhou, G. C.

    1984-01-01

    The capture of newly ionized lithium ions in the solar wind by means of electromagnetic instabilities is investigated through linear analysis and computer simulation. Three instabilities, driven by a lithium velocity ring perpendicular to and drifting along the magnetic field, are considered. The capture time of the lithium by the solar wind is roughly 10 linear growth times, regardless of whether resonant or nonresonant modes dominate initially. Possible implications of the results for the Active Magnetosphere Particle Tracer Explorer (AMPTE) mission are discussed.

  6. Do Ca2+-adsorbing ceramics reduce the release of calcium ions from gypsum-based biomaterials?

    PubMed

    Belcarz, Anna; Zalewska, Justyna; Pałka, Krzysztof; Hajnos, Mieczysław; Ginalska, Grazyna

    2015-02-01

    Bone implantable materials based on calcium sulfate dihydrate dissolve quickly in tissue liquids and release calcium ions at very high levels. This phenomenon induces temporary toxicity for osteoblasts, may cause local inflammation and delay the healing process. Reduction in the calcium ion release rate by gypsum could be therefore beneficial for the healing of gypsum-filled bone defects. The aim of this study concerned the potential use of calcium phosphate ceramics of various porosities for the reduction of high Ca(2+) ion release from gypsum-based materials. Highly porous ceramics failed to reduce the level of Ca(2+) ions released to the medium in a continuous flow system. However, it succeeded to shorten the period of high calcium level. It was not the phase composition but the high porosity of ceramics that was found crucial for both the shortening of the Ca(2+) release-related toxicity period and intensification of apatite deposition on the composite. Nonporous ceramics was completely ineffective for this purpose and did not show any ability to absorb calcium ions at a significant level. Moreover, according to our observations, complex studies imitating in vivo systems, rather than standard tests, are essential for the proper evaluation of implantable biomaterials.

  7. Radioactive Fission Product Release from Defective Light Water Reactor Fuel Elements

    SciTech Connect

    Konyashov, Vadim V.; Krasnov, Alexander M.

    2002-04-15

    Results are provided of the experimental investigation of radioactive fission product (RFP) release, i.e., krypton, xenon, and iodine radionuclides from fuel elements with initial defects during long-term (3 to 5 yr) irradiation under low linear power (5 to 12 kW/m) and during special experiments in the VK-50 vessel-type boiling water reactor.The calculation model for the RFP release from the fuel-to-cladding gap of the defective fuel element into coolant was developed. It takes into account the convective transport in the fuel-to-cladding gap and RFP sorption on the internal cladding surface and is in good agreement with the available experimental data. An approximate analytical solution of the transport equation is given. The calculation dependencies of the RFP release coefficients on the main parameters such as defect size, fuel-to-cladding gap, temperature of the internal cladding surface, and radioactive decay constant were analyzed.It is shown that the change of the RFP release from the fuel elements with the initial defects during long-term irradiation is, mainly, caused by fuel swelling followed by reduction of the fuel-to-cladding gap and the fuel temperature. The calculation model for the RFP release from defective fuel elements applicable to light water reactors (LWRs) was developed. It takes into account the change of the defective fuel element parameters during long-term irradiation. The calculation error according to the program does not exceed 30% over all the linear power change range of the LWR fuel elements (from 5 to 26 kW/m)

  8. Polyamide/silver antimicrobials: effect of filler types on the silver ion release.

    PubMed

    Kumar, Radhesh; Howdle, Steve; Münstedt, Helmut

    2005-11-01

    The efficiency of various silver-based antimicrobial fillers (elementary silver and silver substituted materials) in polyamide (PA) toward their silver ion (Ag+) release characteristics in an aqueous medium was investigated and discussed. Anode stripping voltammetry (ASV) was used for the quantitative estimation of Ag+ release from these composites. The biocidal (Ag+) release from the composites was found to be dependent on the time of soaking in water and the nature of the filler. The long-term Ag+ release capability of the elementary silver-based PA/Ag composite is promising compared with the commercial counterparts. The silver ion release potential of polyamide composites where the silver filling was performed by using supercritical carbon dioxide (scCO2) is also discussed. The composites release Ag+ at a concentration level capable of rendering antimicrobial efficacy and proved to be active against the microbes. A good agreement exists between the Ag+ release experiments and antimicrobial test results. The observed results on the influence of the nature of the filler and crystallinity on the biocidal release and the varying long-term release properties could be helpful in the design of industrially relevant biomaterials.

  9. Virulence modulation of Candida albicans biofilms by metal ions commonly released from orthodontic devices.

    PubMed

    Ronsani, Maiara Medeiros; Mores Rymovicz, Alinne Ulbrich; Meira, Thiago Martins; Trindade Grégio, Ana Maria; Guariza Filho, Odilon; Tanaka, Orlando Motohiro; Ribeiro Rosa, Edvaldo Antonio

    2011-12-01

    The installation of metal devices leads to an increase in the salivary concentration of metal ions and in the growth of salivary Candida spp. However, the relationship between released metal ions and Candida virulence has not been previously examined. The objective of this study was to evaluate whether metal ions affect fungal virulence. We prepared culture media containing Ni(2+), Fe(3+), Cr(3+), Co(2+) or a mixture of these metal ions at concentrations similar to those released in saliva of orthodontic patients. Biofilms of Candida albicans SC5314 were grown for 72 h and their biomasses were determined. The supernatants were analyzed for secretory aspartyl protease (SAP) and hemolysin activities. To verify changes in virulence following treatment with metals, proteolytic and hemolytic activities were converted into specific activities. The results revealed that all ions, except Co(2+), caused increases in biofilm biomass. In addition, Ni(2+) caused an increase in SAP activity and Fe(3+) reduced hemolytic activity. However, the SAP and hemolysin activities in the presence of the mixture of ions did not differ from those of control. These results indicate that metal ions released during the degradation of orthodontic appliances can modulate virulence factors in C. albicans biofilms.

  10. The effect of composition on ion release from Ca-Sr-Na-Zn-Si glass bone grafts.

    PubMed

    Murphy, S; Boyd, D; Moane, S; Bennett, M

    2009-11-01

    Controlled delivery of active ions from biomaterials has become critical in bone regeneration. Some silica-based materials, in particular bioactive glasses, have received much attention due to the ability of their dissolution products to promote cell proliferation, cell differentiation and activate gene expression. However, many of these materials offer little therapeutic potential for diseased tissue. Incorporating trace elements, such as zinc and strontium, known to have beneficial and therapeutic effects on bone may provide a more viable bone graft option for those suffering from metabolic bone diseases such as osteoporosis. Rational compositional design may also allow for controlled release of these active ions at desirable dose levels in order to enhance therapeutic efficacy. In this study, six differing compositions of calcium-strontium-sodium-zinc-silicate (Ca-Sr-Na-Zn-Si) glass bone grafts were immersed in pH 7.4 and pH 3 solutions to study the effect of glass composition on zinc and strontium release in a normal and extreme physiological environment. The zinc release levels over 30 days for all zinc-containing glasses in the pH 7.4 solution were 3.0-7.65 ppm. In the more acidic pH 3 environment, the zinc levels were higher (89-750 ppm) than those reported to be beneficial and may produce cytotoxic or negative effects on bone tissue. Strontium levels released from all examined glasses in both pH environments similarly fell within apparent beneficial ranges--7.5-3500 ppm. Glass compositions with identical SrO content but lower ZnO:Na(2)O ratios, showed higher levels of Sr(2+) release. Whereas, zinc release from zinc-containing glasses appeared related to ZnO compositional content. Sustainable strontium and zinc release was seen in the pH 7.4 environment up to day 7. These results indicate that the examined Ca-Sr-Na-Zn-Si glass compositions show good potential as therapeutic bone grafts, and that the graft composition can be tailored to allow therapeutic

  11. On the transport of ions released in the magnetotail by the AMPTE-IRM satellite

    NASA Technical Reports Server (NTRS)

    Cladis, J. B.; Francis, W. E.

    1988-01-01

    The Ba and Li ions releasd into the magnetotail in spring 1985 by the AMPTE-IRM satellite were not observed subsequently in the inner magnetosphere with the AMPTE-CCE satellite. These results were studied by using a Monte Carlo code to compute the transport of the ions. For each release several hundred ion guiding-center trajectories were computed under simulated magnetospheric conditions, using the Tsyganenko-Usmanov (1982) magnetic-field model and the Millstone Hill convection-electric-field model (Oliver et al., 1983). The corotation and convection electric fields were mapped to altitudes above the ionosphere, assuming the magnetic-field lines to be equipotentials. The initial conditions of the ions, at the times at which the ions were picked up by the electric field, were estimated by taking into consideration the release conditions and the early-time collective effects. The results indicate that the Ba(+) ions were not observed because the CCE satellite was not along the drift paths of the ions, and the Li(+) ions were not observed because their fluxes at the satellite were too low.

  12. An invitro analysis of elemental release and cytotoxicity of recast nickel-chromium dental casting alloys.

    PubMed

    Reddy, Nagam Raja; Abraham, Anandapandian Ponsekar; Murugesan, Krishnan; Matsa, Vasanthakumar

    2011-06-01

    Recasting of the casting alloys affects the composition and elemental release which may have cytotoxic effect different from the pure alloy in the surrounding tissues. An Invitro study was conducted to investigate the elemental release and their cytotoxic effects from commercially available Ni-Cr dental casting alloys, commonly used for fabricating fixed partial dentures. Three Ni-Cr alloys [Wiron 99(A), Ceramet (B), and Hi Nickel CB (C)] were tested. Alloy specimens (disks 3 × 5 mm) were casted and grouped as follows: Group I (A(1)/B(1)/C(1)): 100% pure alloy; Group II (A(2)/B(2)/C(2)): 50% new with 50% recast; and Group III (A(3)/B(3)/C(3)): 100% recast. Disks of each alloy type from each group were transferred to Dulbecco's modified eagle medium and left for 3 days at 37°C in an atmosphere of 5% CO(2). Ni, Cr, Co, Cu and Mo elemental release from metal alloys into culture medium was investigated using Inductively Coupled Plasma Mass Spectrometry. Cytotoxicity was tested using mouse fibroblast cells and MTT Assay. Controls consisted of 6 wells containing cells with no alloy specimens. Data were analyzed by two-way analysis of variance followed by t-test. The total amount of elements released in parts per billion for various casting groups were Group I, A(1)-6.572, B(1)-6.732, C(1)-8.407; Group II, A(2)-22.046, B(2)-26.450, C(2)-29.189; Group III, A(3)-84.554, B(3)-88.359, C(3)-92.264. More amounts of elements were released in Hi Nickel CB than Ceramet and Wiron 99 in all the three test groups. Percentage of viable cells from MTT analysis were Group I, A(1)-62.342, B(1)-61.322 C(1)-60.593, Group II, A(2)-58.699, B(2)-56.494, C(2)-52.688, Group III, A(3)-53.101, B(3)-52.195, C(3)-47.586. The viable cells present in the culture media were more in Wiron 99 than Ceramet and Hi Nickel CB. Elemental release increased with amount of recast alloy. Amongst the three alloys tested Hi Nickel CB had significantly higher elements released compared to Ceramet and Wiron 99

  13. Antimicrobial Activity of Silver Ions Released from Zeolites Immobilized on Cellulose Nanofiber Mats.

    PubMed

    Rieger, Katrina A; Cho, Hong Je; Yeung, Hiu Fai; Fan, Wei; Schiffman, Jessica D

    2016-02-10

    In this study, we exploit the high silver ion exchange capability of Linde Type A (LTA) zeolites and present, for the first time, electrospun nanofiber mats decorated with in-house synthesized silver (Ag(+)) ion exchanged zeolites that function as molecular delivery vehicles. LTA-Large zeolites with a particle size of 6.0 μm were grown on the surface of the cellulose nanofiber mats, whereas LTA-Small zeolites (0.2 μm) and three-dimensionally ordered mesoporous-imprinted (LTA-Meso) zeolites (0.5 μm) were attached to the surface of the cellulose nanofiber mats postsynthesis. After the three zeolite/nanofiber mat assemblies were ion-exchanged with Ag(+) ions, their ion release profiles and ability to inactivate Escherichia coli (E. coli) K12 were evaluated as a function of time. LTA-Large zeolites immobilized on the nanofiber mats displayed more than an 11 times greater E. coli K12 inactivation than the Ag-LTA-Large zeolites that were not immobilized on the nanofiber mats. This study demonstrates that by decorating nanometer to micrometer scale Ag(+) ion-exchanged zeolites on the surface of high porosity, hydrophilic cellulose nanofiber mats, we can achieve a tunable release of Ag(+) ions that inactivate bacteria faster and are more practical to use in applications over powder zeolites.

  14. Release of elements to natural water from sediments of Lake Roosevelt, Washington, USA

    USGS Publications Warehouse

    Paulson, Anthony J.; Cox, Stephen E.

    2007-01-01

    Reservoir sediments from Lake Roosevelt (WA, USA) that were contaminated with smelter waste discharged into the Columbia River (BC, Canada) were examined using three measures of elemental release reflecting varying degrees of physical mixing and time scales. Aqueous concentrations of Cd, Cu, Pb, and Zn in the interstitial water of reservoir sediments, in the gently stirred overlying waters of incubated sediment cores, and in supernatants of aggressively tumbled slurries of reservoir sediments generally were higher than the concentrations from a reference site. When compared to chronic water-quality criteria, all three measures of release suggest that slag-contaminated sediments near the U.S.-Canadian border are potentially toxic as a result of Cu release and Pb release in two of the three measures. All three measures of Cd release suggest potential toxicity for one site farther down the reservoir, probably contaminated as a result of transport and adsorption of Cd from smelter liquid waste. Releases of Zn and As did not appear to be potentially toxic. Carbonate geochemistry indirectly affects the potential toxicity by increasing water hardness.

  15. Swift heavy ion irradiation of interstellar dust analogues. Small carbonaceous species released by cosmic rays

    NASA Astrophysics Data System (ADS)

    Dartois, E.; Chabot, M.; Pino, T.; Béroff, K.; Godard, M.; Severin, D.; Bender, M.; Trautmann, C.

    2017-03-01

    Context. Interstellar dust grain particles are immersed in vacuum ultraviolet (VUV) and cosmic ray radiation environments influencing their physicochemical composition. Owing to the energetic ionizing interactions, carbonaceous dust particles release fragments that have direct impact on the gas phase chemistry. Aims: The exposure of carbonaceous dust analogues to cosmic rays is simulated in the laboratory by irradiating films of hydrogenated amorphous carbon interstellar analogues with energetic ions. New species formed and released into the gas phase are explored. Methods: Thin carbonaceous interstellar dust analogues were irradiated with gold (950 MeV), xenon (630 MeV), and carbon (43 MeV) ions at the GSI UNILAC accelerator. The evolution of the dust analogues is monitored in situ as a function of fluence at 40, 100, and 300 K. Effects on the solid phase are studied by means of infrared spectroscopy complemented by simultaneously recording mass spectrometry of species released into the gas phase. Results: Specific species produced and released under the ion beam are analyzed. Cross sections derived from ion-solid interaction processes are implemented in an astrophysical context.

  16. Biological phosphate uptake and release: effect of pH and magnesium ions.

    PubMed

    Wu, Qingzhong; Bishop, Paul L; Keener, Tim C

    2006-02-01

    Enhanced biological phosphorus removal (EBPR) is based on poly-phosphate accumulating organisms' (PAOs) unique features of "luxury" phosphate uptake during aerobic conditions and phosphate release in anaerobic conditions. It is believed that poly-phosphate accumulation is accompanied by the uptake and accumulation of potassium ions (K+) and magnesium ions (Mg2+). The release of phosphate under anaerobic conditions is also accompanied by the release of both cations. The objective of this research was to evaluate the effect of pH and Mg2+ on the biological phosphate uptake and release behavior of activated sludge mixed liquor during aeration and sedimentation. Research results indicate that Mg2+, supplied either by magnesium chloride (MgCl2) or magnesium hydroxide [Mg(OH)2], stimulated phosphate uptake during the aeration period, while pH increase, caused by the application of Mg(OH)2, enhanced phosphate release during the sedimentation period. It is also noted in our experiments with MgCl2 that Mg2+ slightly inhibited anaerobic phosphate release.

  17. Intracellular accumulation of indium ions released from nanoparticles induces oxidative stress, proinflammatory response and DNA damage.

    PubMed

    Tabei, Yosuke; Sonoda, Akinari; Nakajima, Yoshihiro; Biju, Vasudevanpillai; Makita, Yoji; Yoshida, Yasukazu; Horie, Masanori

    2016-02-01

    Due to the widespread use of indium tin oxide (ITO), it is important to investigate its effect on human health. In this study, we evaluated the cellular effects of ITO nanoparticles (NPs), indium chloride (InCl3) and tin chloride (SnCl3) using human lung epithelial A549 cells. Transmission electron microscopy and inductively coupled plasma mass spectrometry were employed to study cellular ITO NP uptake. Interestingly, greater uptake of ITO NPs was observed, as compared with soluble salts. ITO NP species released could be divided into two types: 'indium release ITO' or 'tin release ITO'. We incubated A549 cells with indium release ITO, tin release ITO, InCl3 or SnCl2 and investigated oxidative stress, proinflammatory response, cytotoxicity and DNA damage. We found that intracellular reactive oxygen species were increased in cells incubated with indium release ITO, but not tin release ITO, InCl3 or SnCl2. Messenger RNA and protein levels of the inflammatory marker, interleukin-8, also increased following exposure to indium release ITO. Furthermore, the alkaline comet assay revealed that intracellular accumulation of indium ions induced DNA damage. Our results demonstrate that the accumulation of ionic indium, but not ionic tin, from ITO NPs in the intracellular matrix has extensive cellular effects.

  18. Intracellular accumulation of indium ions released from nanoparticles induces oxidative stress, proinflammatory response and DNA damage

    PubMed Central

    Tabei, Yosuke; Sonoda, Akinari; Nakajima, Yoshihiro; Biju, Vasudevanpillai; Makita, Yoji; Yoshida, Yasukazu; Horie, Masanori

    2016-01-01

    Due to the widespread use of indium tin oxide (ITO), it is important to investigate its effect on human health. In this study, we evaluated the cellular effects of ITO nanoparticles (NPs), indium chloride (InCl3) and tin chloride (SnCl3) using human lung epithelial A549 cells. Transmission electron microscopy and inductively coupled plasma mass spectrometry were employed to study cellular ITO NP uptake. Interestingly, greater uptake of ITO NPs was observed, as compared with soluble salts. ITO NP species released could be divided into two types: ‘indium release ITO’ or ‘tin release ITO’. We incubated A549 cells with indium release ITO, tin release ITO, InCl3 or SnCl2 and investigated oxidative stress, proinflammatory response, cytotoxicity and DNA damage. We found that intracellular reactive oxygen species were increased in cells incubated with indium release ITO, but not tin release ITO, InCl3 or SnCl2. Messenger RNA and protein levels of the inflammatory marker, interleukin-8, also increased following exposure to indium release ITO. Furthermore, the alkaline comet assay revealed that intracellular accumulation of indium ions induced DNA damage. Our results demonstrate that the accumulation of ionic indium, but not ionic tin, from ITO NPs in the intracellular matrix has extensive cellular effects. PMID:26378248

  19. Cytotoxicity of copper ions released from metal: variation with the exposure period and concentration gradients.

    PubMed

    Cortizo, María Cecilia; Fernández Lorenzo de Mele, Mónica

    2004-01-01

    The aim of this work is to contribute to the elucidation of the cytotoxic process caused by the copper ions released from the biomaterials. Clonal cell lines UMR106 were used in the experiments. Copper ions were obtained from two different sources: copper salts and metal dissolution. Experiments carried out with constant ion concentrations (copper salts) were compared with those with concentrations that vary with time and location (dissolution of the metal). Present results and others previously reported could be interpreted through mathematical models that describe: (1) the variation of concentration of copper ions with time and location within a biofilm and (2) the variation of the killing rate with the concentration of the toxic ion and time. The large number of dead cells found near the copper sample with an average ion concentration below the toxic limit could be interpreted bearing in mind that these cells should be exposed to a local concentration higher than this limit. A logarithmic dependence between the number of cells and exposure time was found for nearly constant ion concentrations. Apparent discrepancies, observed when these results and those of different researchers were contrasted, could be explained considering the dissimilar experimental conditions such as the source of the ions and their local concentration at real time.

  20. Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles

    PubMed Central

    Chen, Chen; Weir, Michael D.; Cheng, Lei; Lin, Nancy; Lin-Gibson, Sheng; Chow, Laurence C.; Zhou, Xuedong; Xu, Hockin H. K.

    2015-01-01

    Objectives Recurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties. Methods Nanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4. Results Adding 5% DMADDM and 10–40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p > 0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6–10 folds. Significance Bonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was “smart” and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent

  1. Elemental mercury releases attributed to antiques--New York, 2000-2006.

    PubMed

    2007-06-15

    Metallic (i.e., elemental) mercury, a heavy, silvery odorless liquid, is in common household products such as thermostats and thermometers. Lesser-known household sources of elemental mercury include certain antique or vintage items such as clocks, barometers, mirrors, and lamps. Over time, the mercury in these items can leak, particularly as seals age or when the items are damaged, dropped, or moved improperly. Vacuuming a mercury spill or vaporization from spill-contaminated surfaces such as carpets, floors, furniture, mops, or brooms can increase levels of mercury in the air, especially in enclosed spaces. Environmental sampling conducted after releases of elemental mercury have indicated substantial air concentrations that were associated with increases in blood and urine mercury levels among exposed persons. In 1990, the Agency for Toxic Substances and Disease Registry (ATSDR) created the Hazardous Substances Emergency Events Surveillance (HSEES) system, a multistate health department surveillance system designed to help reduce morbidity and mortality associated with hazardous substance events. This report describes antique-related mercury releases reported to HSEES, all of which occurred in New York state during 2000-2006. Although none of these spills resulted in symptoms or acute health effects, they required remediation to prevent future mercury exposure. The findings underscore the need for caution when handling antiques containing elemental mercury and the need for proper remediation of spills.

  2. Finite Element Analysis of Silicon Thin Films on Soft Substrates as Anodes for Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Shaffer, Joseph

    2011-12-01

    The wide-scale use of green technologies such as electric vehicles has been slowed due to insufficient means of storing enough portable energy. Therefore it is critical that efficient storage mediums be developed in order to transform abundant renewable energy into an on-demand source of power. Lithium (Li) ion batteries are seeing a stream of improvements as they are introduced into many consumer electronics, electric vehicles and aircraft, and medical devices. Li-ion batteries are well suited for portable applications because of their high energy-to-weight ratios, high energy densities, and reasonable life cycles. Current research into Li-ion batteries is focused on enhancing its energy density, and by changing the electrode materials, greater energy capacities can be realized. Silicon (Si) is a very attractive option because it has the highest known theoretical charge capacity. Current Si anodes, however, suffer from early capacity fading caused by pulverization from the stresses induced by large volumetric changes that occur during charging and discharging. An innovative system aimed at resolving this issue is being developed. This system incorporates a thin Si film bonded to an elastomeric substrate which is intended to provide the desired stress relief. Non-linear finite element simulations have shown that a significant amount of deformation can be accommodated until a critical threshold of Li concentration is reached; beyond which buckling is induced and a wavy structure appears. When compared to a similar system using rigid substrates where no buckling occurs, the stress is reduced by an order of magnitude, significantly prolonging the life of the Si anode. Thus the stress can be released at high Li-ion diffusion induced strains by buckling the Si thin film. Several aspects of this anode system have been analyzed including studying the effects of charge rate and thin film plasticity, and the results are compared with preliminary empirical measurements to

  3. Development and Evaluation of Oral Controlled Release Chlorpheniramine-Ion Exchange Resinate Suspension

    PubMed Central

    Kadam, A. U.; Sakarkar, D. M.; Kawtikwar, P. S.

    2008-01-01

    An oral controlled release suspension of chlorpheniramine maleate was prepared using ion-exchange resin technology. A strong cation exchange resin Indion 244 was utilized for the sorption of the drug and the drug resinates was evaluated for various physical and chemical parameters. The drug-resinate complex was microencapsulated with a polymer Eudragit RS 100 to further retard the release characteristics. Both the drug-resinate complex and microencapsulated drug resinate were suspended in a palatable aqueous suspension base and were evaluated for controlled release characteristic. Stability study indicated that elevated temperature did not alter the sustained release nature of the dosage form indicating that polymer membrane surrounding the core material remained intact throughout the storage period. PMID:20046790

  4. Heavy Ion Inertial Fusion Energy: Summaries of Program Elements

    SciTech Connect

    Friedman, A; Barnard, J J; Kaganovich, I; Seidl, P A; Briggs, R J; Faltens, A; Kwan, J W; Lee, E P; Logan, B G

    2011-02-28

    The goal of the Heavy Ion Fusion (HIF) Program is to apply high-current accelerator technology to IFE power production. Ion beams of mass {approx}100 amu and kinetic energy {>=} 1 GeV provide efficient energy coupling into matter, and HIF enjoys R&D-supported favorable attributes of: (1) the driver, projected to be robust and efficient; see 'Heavy Ion Accelerator Drivers.'; (2) the targets, which span a continuum from full direct to full indirect drive (and perhaps fast ignition), and have metal exteriors that enable injection at {approx}10 Hz; see 'IFE Target Designs'; (3) the near-classical ion energy deposition in the targets; see 'Beam-Plasma Interactions'; (4) the magnetic final lens, robust against damage; see 'Final Optics-Heavy Ion Beams'; and (5) the fusion chamber, which may use neutronically-thick liquids; see 'Liquid-Wall Chambers.' Most studies of HIF power plants have assumed indirect drive and thick liquid wall protection, but other options are possible.

  5. Ionization potentials of superheavy elements No, Lr, and Rf and their ions

    PubMed Central

    Dzuba, V. A.; Safronova, M. S.; Safronova, U. I.; Kramida, A.

    2016-01-01

    We predict ionization potentials of superheavy elements No, Lr, and Rf and their ions using a relativistic hybrid method that combines configuration interaction (CI) with the linearized coupled-cluster approach. Extensive study of the completeness of the four-electron CI calculations for Hf and Rf was carried out. As a test of theoretical accuracy, we also calculated ionization potential of Yb, Lu, Hf, and their ions, which are homologues of the superheavy elements of this study. PMID:28058290

  6. Ionization potentials of superheavy elements No, Lr, and Rf and their ions

    NASA Astrophysics Data System (ADS)

    Dzuba, V. A.; Safronova, M. S.; Safronova, U. I.; Kramida, A.

    2016-10-01

    We predict ionization potentials of superheavy elements No, Lr, and Rf and their ions using a relativistic hybrid method that combines configuration interaction (CI) with the linearized coupled-cluster approach. Extensive study of the completeness of the four-electron CI calculations for Hf and Rf was carried out. As a test of theoretical accuracy, we also calculated ionization potential of Yb, Lu, Hf, and their ions, which are homologues of the superheavy elements of this study.

  7. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    SciTech Connect

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-05-01

    A method to automatically identify possible elemental ions in X-ray crystal structures has been extended to use support vector machine (SVM) classifiers trained on selected structures in the PDB, with significantly improved sensitivity over manually encoded heuristics. In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.

  8. Use of biogenic and abiotic elemental selenium nanospheres to sequester elemental mercury released from mercury contaminated museum specimens.

    PubMed

    Fellowes, J W; Pattrick, R A D; Green, D I; Dent, A; Lloyd, J R; Pearce, C I

    2011-05-30

    Mercuric chloride solutions have historically been used as pesticides to prevent bacterial, fungal and insect degradation of herbarium specimens. The University of Manchester museum herbarium contains over a million specimens from numerous collections, many preserved using HgCl(2) and its transformation to Hg(v)(0) represents a health risk to herbarium staff. Elevated mercury concentrations in work areas (∼ 1.7 μg m(-3)) are below advised safe levels (<25 μg m(-3)) but up to 90 μg m(-3) mercury vapour was measured in specimen boxes, representing a risk when accessing the samples. Mercury vapour release correlated strongly with temperature. Mercury salts were observed on botanical specimens at concentrations up to 2.85 wt% (bulk); XPS, SEM-EDS and XANES suggest the presence of residual HgCl(2) as well as cubic HgS and HgO. Bacterially derived, amorphous nanospheres of elemental selenium effectively sequestered the mercury vapour in the specimen boxes (up to 19 wt%), and analysis demonstrated that the Hg(v)(0) was oxidised by the selenium to form stable HgSe on the surface of the nanospheres. Biogenic Se(0) can be used to reduce Hg(v)(0) in long term, slow release environments.

  9. pH-dependent release of trace elements including platinum group elements (PGEs) from gasoline and diesel catalysts

    NASA Astrophysics Data System (ADS)

    Sucha, Veronika; Mihaljevic, Martin; Ettler, Vojtech; Strnad, Ladislav

    2014-05-01

    The release of trace metals and platinum group elements (PGEs) from automobile exhaust catalysts represents a remarkable source of higly dispersed environmental contamination. Especially, PGEs have shown increasing research interest due to their possible bioaccessibility. In our research, we focused on leaching behaviour of trace metals from gasoline and diesel automobile catalysts. While catalysts for gasoline engines contain a mixture of Pt-Pd-Rh or Pd-Rh, catalysts for diesel engines are composed only of Pt. We used dust from two crushed gasoline and two crushed diesel catalysts (new and aged). The dust of gasoline catalysts contains significant concentrations of Pt (700 mg.kg-1), Pd (11 000 mg.kg-1) and Rh (700 mg.kg-1). And the dust of diesel catalysts are composed of Pt (3 900 mg.kg-1) and they contains negligible amounts of Pd dan Rh (< 0.5 mg.kg-1, < 0.1 mg.kg-1, respectively). To evaluate leaching of trace metals from dust we used pH-stat leaching test according to the European standard CEN/TS 14997. The concentrations of cations: PGEs (Pt, Pd a Rh), K, Na, Ca, Mg, Al, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, La and Ce were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic absorption spectrometry (AAS), and anions: F-, Cl-, SO42- and NO3- by high-performance liquid chromatography. Although the dusts from catalysts were relatively stable to acid/base influence, the leaching of trace metals from catalysts showed a dependence on pH. Generally, the highest concentrations were released under acidic conditions. The leaching of PGEs was higher for Pt in diesel catalysts and for Pd and Rh in gasoline catalysts. The highest concentrations of Zn and Pb were observed in old catalysts. The rare earth metals were released more from gasoline catalysts. Catalysts particles represent health risk especially with respect to their PGEs contents.

  10. Nanoscale surface structuring during ion bombardment of elemental semiconductors

    NASA Astrophysics Data System (ADS)

    Anzenberg, Eitan

    2013-01-01

    Nano-patterning of surfaces with uniform ion bombardment yields a rich phase-space of topographic patterns. Particle irradiation can cause surface ultra-smoothing or self-organized nanoscale pattern formation in surface topography. Topographic pattern formation has previously been attributed to the effects of the removal of target atoms by sputter erosion. In this thesis, the surface morphology evolution of Si(100) and Ge(100) during low energy ion bombardment of Ar+ and Kr+ ions, respectively, is studied. Our facilities for studies of surface processes at the National Synchrotron Light Source (NSLS) allow in-situ characterization of surface morphology evolution during ion bombardment using grazing incidence small angle x-ray scattering (GISAXS). This technique is used to measure in reciprocal space the kinetics of formation or decay of correlated nanostructures on the surface, effectively measuring the height-height correlations. A linear model is used to characterize the early time kinetic behavior during ion bombardment as a function of ion beam incidence angle. The curvature coefficients predicted by the widely used erosive model of Bradley and Harper are quantitatively negligible and of the wrong sign when compared to the observed effect in both Si and Ge. A mass-redistribution model explains the observed ultra-smoothing at low angles, exhibits an instability at higher angles, and predicts the observed 45° critical angle separating these two regimes in Si. The Ge surface evolution during Kr+ irradiation is qualitatively similar to that observed for Ar+ irradiation of Si at the same ion energy. However, the critical angle for Ge cannot be quantitatively reproduced by the simple mass redistribution model. Crater function theory, as developed by Norris et al., incorporates both mass redistributive and erosive effects, and predicts constraining relationships between curvature coefficients. These constraints are compared to experimental data of both Si and Ge

  11. Trace elements release from volcanic ash to seawater. Natural concentrations in Central Mediterranean sea

    NASA Astrophysics Data System (ADS)

    Randazzo, L. A.; Censi, P.; Saiano, F.; Zuddas, P.; Aricò, P.; Mazzola, S.

    2009-04-01

    element leaching occurs through a first quick followed by a slow second step that attaints to an apparent equilibrium after 6 months. Amplitude of kinetic rate constant measured for SiO2 release during the first step and behaviour of Ti/Si and Cr/Si rations in primary volcanic minerals, glass fraction and leaching solutions during the first 1 month stage of the experimental interaction allowed to demonstrate that trace element release mainly occurs from glassy materials and Ti-rich magnetite.

  12. Surface analysis of all elements with isotopic resolution at high ambient pressures using ion spectroscopic techniques

    SciTech Connect

    Smentkowski, V.S.; Krauss, A.R.; Gruen, D.M.; Holecek, J.C.; Schultz, J.A.

    1997-09-01

    The authors have developed a mass spectrometer capable of surface analysis using the techniques of secondary ion mass spectroscopy (SIMS) and mass spectroscopy of recoiled ions (MSRI). For SIMS, an energetic ion beam creates a collision cascade which results in the ejection of low kinetic energy secondary ions from the surface being analyzed. The low kinetic energy SIMS ions are very susceptible to charge neutralization with the surface, and as a result, the SIMS ion yield varies by orders of magnitude depending on the chemical state of the surface. SIM spectra contain elemental ions, and molecular ions. For MSRI, a pulsed ion beam induces a binary collision with the surface being analyzed and the surface species are recoiled into the forward scattering direction with a large kinetic energy. The violence of the binary collision results in complete molecular decomposition, and only elemental ions are detected. The high kinetic energy MSRI ions are much less susceptible to charge neutralization with the surface than the low kinetic energy SIMS ions. In MSRI, the ion yield typically varies by less than a factor of ten as the chemical state of the surface changes--simplifying quantitative analysis vs. SIMS. In this paper, they authors will demonstrate that the high kinetic energy MSRI ions are able to transverse high pressure paths with only a reduction in peak intensity--making MSRI an ideal tool for real-time, in-situ film growth studies. The use of a single analyzer for both MSRI and SIMS is unique and provides complimentary information.

  13. The Influence of Hydrogen Ion Concentration on Calcium Binding and Release by Skeletal Muscle Sarcoplasmic Reticulum

    PubMed Central

    Nakamaru, Yoshiaki; Schwartz, Arnold

    1972-01-01

    Calcium release and binding produced by alterations in pH were investigated in isolated sarcoplasmic reticulum (SR) from skeletal muscle. When the pH was abruptly increased from 6.46 to 7.82, after calcium loading for 30 sec, 80–90 nanomoles (nmole) of calcium/mg protein were released. When the pH was abruptly decreased from 7.56 to 6.46, after calcium loading for 30 sec, 25–30 nmole of calcium/mg protein were rebound. The calcium release process was shown to be a function of pH change: 57 nmole of calcium were released per 1 pH unit change per mg protein. The amount of adenosine triphosphate (ATP) bound to the SR was not altered by the pH changes. The release phenomenon was not due to alteration of ATP concentration by the increased pH. Native actomyosin was combined with SR in order to study the effectiveness of calcium release from the SR by pH change in inducing super-precipitation of actomyosin. It was found that SR, in an amount high enough to inhibit superprecipitation at pH 6.5, did not prevent the process when the pH was suddenly increased to 7.3, indicating that the affinity of SR for calcium depends specifically on pH. These data suggest the possible participation of hydrogen ion concentration in excitation-contraction coupling. PMID:5007263

  14. Therapeutic ion-releasing bioactive glass ionomer cements with improved mechanical strength and radiopacity

    NASA Astrophysics Data System (ADS)

    Fuchs, Maximilian; Gentleman, Eileen; Shahid, Saroash; Hill, Robert; Brauer, Delia

    2015-10-01

    Bioactive glasses (BG) are used to regenerate bone, as they degrade and release therapeutic ions. Glass ionomer cements (GIC) are used in dentistry, can be delivered by injection and set in situ by a reaction between an acid-degradable glass and a polymeric acid. Our aim was to combine the advantages of BG and GIC, and we investigated the use of alkali-free BG (SiO2-CaO-CaF2-MgO) with 0 to 50% of calcium replaced by strontium, as the beneficial effects of strontium on bone formation are well documented. When mixing BG and poly(vinyl phosphonic-co-acrylic acid), ions were released fast (up to 90% within 15 minutes at pH 1), which resulted in GIC setting, as followed by infrared spectroscopy. GIC mixed well and set to hard cements (compressive strength up to 35 MPa), staying hard when in contact with aqueous solution. This is in contrast to GIC prepared with poly(acrylic acid), which were shown previously to become soft in contact with water. Strontium release from GIC increased linearly with strontium for calcium substitution, allowing for tailoring of strontium release depending on clinical requirements. Furthermore, strontium substitution increased GIC radiopacity. GIC passed ISO10993 cytotoxicity test, making them promising candidates for use as injectable bone cements.

  15. The Gypsy Database (GyDB) of mobile genetic elements: release 2.0.

    PubMed

    Llorens, Carlos; Futami, Ricardo; Covelli, Laura; Domínguez-Escribá, Laura; Viu, Jose M; Tamarit, Daniel; Aguilar-Rodríguez, Jose; Vicente-Ripolles, Miguel; Fuster, Gonzalo; Bernet, Guillermo P; Maumus, Florian; Munoz-Pomer, Alfonso; Sempere, Jose M; Latorre, Amparo; Moya, Andres

    2011-01-01

    This article introduces the second release of the Gypsy Database of Mobile Genetic Elements (GyDB 2.0): a research project devoted to the evolutionary dynamics of viruses and transposable elements based on their phylogenetic classification (per lineage and protein domain). The Gypsy Database (GyDB) is a long-term project that is continuously progressing, and that owing to the high molecular diversity of mobile elements requires to be completed in several stages. GyDB 2.0 has been powered with a wiki to allow other researchers participate in the project. The current database stage and scope are long terminal repeats (LTR) retroelements and relatives. GyDB 2.0 is an update based on the analysis of Ty3/Gypsy, Retroviridae, Ty1/Copia and Bel/Pao LTR retroelements and the Caulimoviridae pararetroviruses of plants. Among other features, in terms of the aforementioned topics, this update adds: (i) a variety of descriptions and reviews distributed in multiple web pages; (ii) protein-based phylogenies, where phylogenetic levels are assigned to distinct classified elements; (iii) a collection of multiple alignments, lineage-specific hidden Markov models and consensus sequences, called GyDB collection; (iv) updated RefSeq databases and BLAST and HMM servers to facilitate sequence characterization of new LTR retroelement and caulimovirus queries; and (v) a bibliographic server. GyDB 2.0 is available at http://gydb.org.

  16. The Gypsy Database (GyDB) of mobile genetic elements: release 2.0

    PubMed Central

    Llorens, Carlos; Futami, Ricardo; Covelli, Laura; Domínguez-Escribá, Laura; Viu, Jose M.; Tamarit, Daniel; Aguilar-Rodríguez, Jose; Vicente-Ripolles, Miguel; Fuster, Gonzalo; Bernet, Guillermo P.; Maumus, Florian; Munoz-Pomer, Alfonso; Sempere, Jose M.; Latorre, Amparo; Moya, Andres

    2011-01-01

    This article introduces the second release of the Gypsy Database of Mobile Genetic Elements (GyDB 2.0): a research project devoted to the evolutionary dynamics of viruses and transposable elements based on their phylogenetic classification (per lineage and protein domain). The Gypsy Database (GyDB) is a long-term project that is continuously progressing, and that owing to the high molecular diversity of mobile elements requires to be completed in several stages. GyDB 2.0 has been powered with a wiki to allow other researchers participate in the project. The current database stage and scope are long terminal repeats (LTR) retroelements and relatives. GyDB 2.0 is an update based on the analysis of Ty3/Gypsy, Retroviridae, Ty1/Copia and Bel/Pao LTR retroelements and the Caulimoviridae pararetroviruses of plants. Among other features, in terms of the aforementioned topics, this update adds: (i) a variety of descriptions and reviews distributed in multiple web pages; (ii) protein-based phylogenies, where phylogenetic levels are assigned to distinct classified elements; (iii) a collection of multiple alignments, lineage-specific hidden Markov models and consensus sequences, called GyDB collection; (iv) updated RefSeq databases and BLAST and HMM servers to facilitate sequence characterization of new LTR retroelement and caulimovirus queries; and (v) a bibliographic server. GyDB 2.0 is available at http://gydb.org. PMID:21036865

  17. Ion channels: Key elements in sea urchin sperm physiology

    NASA Astrophysics Data System (ADS)

    Darszon, Alberto; de De Latorre, Lucia; Vargas, Irma; Liévano, Arturo; Beltrán, Carmen; Santi, Celia; Labarca, Pedro; Zapata, Otilia

    1995-08-01

    Ion channels are deeply involved in sea urchin sperm activation, motility, chemotaxis and in the acrosome reaction. Unraveling ion channel function and regulation in sperm behavior has required a combination of complementary approaches since spermatozoa are very tiny cells. Planar bilayer and patch clamp techniques have allowed us to detect, for the first time, the activity of single channels in the plasma membrane of these cells. Unlike intact sperm, swollen sperm can be much more easily patch clamped and single channel activity recorded. These techniques, together with studies of membrane potential, intracellular Ca2+ and pH in whole sperm, have established the presence of K+, Ca2+, and Cl- channels in this cell. The strategies developed to study sea urchin sperm channels are applicable to mammalian spermatozoa. We recently detected a Ca2+ channel resembling one found in S. purpuratus sperm in planar bilayers containing mouse sperm plasma membranes. The presence of this Ca2+ channel in such diverse species suggests it is important in sperm function.

  18. Effect of simulated rainfall and weathering on release of preservative elements from CCA treated wood.

    PubMed

    Lebow, Stan; Williams, R Sam; Lebow, Patricia

    2003-09-15

    The release of arsenic from wood pressure-treated with chromated copper arsenate (CCA) can be decreased by application of wood finishes, but little is known about the types of finishes that are best suited for this purpose. This study evaluated the effects of finish water repellent content and ultraviolet (UV) radiation on the release of arsenic, copper, and chromium from CCA-treated wood exposed to simulated rainfall. Deck boards treated with CCA were either left unfinished or dipped in a finish prepared with 1%, 3%, or 5% water repellent. All specimens were exposed to leaching from simulated rainfall, and a subset of specimens was also exposed to UV radiation. The rainfall was collected and analyzed for total elemental arsenic, copper, and chromium. The water repellent significantly decreased the amounts of these elements in the runoff, but for the short duration of this study there was no difference among the three water repellent concentrations. It is possible that water repellent content would have a greater effect over a longer exposure period. Exposure to UV radiation caused a significant increase in leaching from both finished and unfinished specimens. This effect may be a result of increased surface area during weathering as well as loss of fibers caused by UV-induced surface erosion.

  19. Real-time monitoring of inhibitory effects on glutamate-induced neurotransmitter release using a potassium ion image sensor

    NASA Astrophysics Data System (ADS)

    Kono, Akiteru; Sakurai, Takashi; Hattori, Toshiaki; Okumura, Koichi; Ishida, Makoto; Sawada, Kazuaki

    2015-02-01

    To directly image the release of neurotransmitters from neurons, we combined a substance-selective layer with a 128 × 128-pixel ion image sensor based on CMOS technology. Using the substance-specific image sensors, we studied the dynamics of potassium ion ( K+) release from neurons and examined the effect of ouabain on K+ release. K+ transients were significantly inhibited by ouabain. The K+ image sensor used in this study demonstrated the dynamic analysis of ligand-operated signal release and the pharmacological assessment of secretagogues without requiring cell labeling.

  20. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    DOE PAGES

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-04-25

    In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalousmore » diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.« less

  1. Using support vector machines to improve elemental ion identification in macromolecular crystal structures

    SciTech Connect

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D.

    2015-04-25

    In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.

  2. Using support vector machines to improve elemental ion identification in macromolecular crystal structures.

    PubMed

    Morshed, Nader; Echols, Nathaniel; Adams, Paul D

    2015-05-01

    In the process of macromolecular model building, crystallographers must examine electron density for isolated atoms and differentiate sites containing structured solvent molecules from those containing elemental ions. This task requires specific knowledge of metal-binding chemistry and scattering properties and is prone to error. A method has previously been described to identify ions based on manually chosen criteria for a number of elements. Here, the use of support vector machines (SVMs) to automatically classify isolated atoms as either solvent or one of various ions is described. Two data sets of protein crystal structures, one containing manually curated structures deposited with anomalous diffraction data and another with automatically filtered, high-resolution structures, were constructed. On the manually curated data set, an SVM classifier was able to distinguish calcium from manganese, zinc, iron and nickel, as well as all five of these ions from water molecules, with a high degree of accuracy. Additionally, SVMs trained on the automatically curated set of high-resolution structures were able to successfully classify most common elemental ions in an independent validation test set. This method is readily extensible to other elemental ions and can also be used in conjunction with previous methods based on a priori expectations of the chemical environment and X-ray scattering.

  3. Ions Release and pH of Calcium Hydroxide-, Chlorhexidine- and Bioactive Glass-Based Endodontic Medicaments.

    PubMed

    Carvalho, Ceci Nunes; Freire, Laila Gonzales; Carvalho, Alexandre Pinheiro Lima de; Duarte, Marco Antonio Húngaro; Bauer, José; Gavini, Giulio

    2016-01-01

    This study evaluated pH and release of calcium, sodium and phosphate ions from different medications in human dentin. Fifty premolars were prepared and randomly divided into groups: (CHX) - 2% chlorhexidine gel; (CHX + CH) - CHX + calcium hydroxide PA; (CH) - CH + propylene glycol 600; (NPBG) - experimental niobium phosphate bioactive glass + distilled water; (BG) - bioactive glass (Bio-Gran) + distilled water. The specimens were immersed in deionized water and the pH variations were measured. The quantification of ions in the solutions was made by inductively coupled plasma - atomic emission spectroscopy (ICP/AES) at 10 min, 24 h, 7, 14, 21 and 30 days. The results were analyzed by ANOVA and Tukey`s test, with a significance level of 5%. CH had the highest level of calcium ions release at 30 days, while CHX and BG released more sodium ions. BG, NPBG and CHX released a higher amount of phosphate ions. The pH of CH was significantly higher compared with the other groups. CH favored the greatest increase of pH and calcium ions release. The bioactive glasses released more sodium and phosphate ions and presented an alkaline pH immediately and after 30 days.

  4. Effect of denture cleansers on metal ion release and surface roughness of denture base materials.

    PubMed

    Davi, Letícia Resende; Felipucci, Daniela Nair Borges; de Souza, Raphael Freitas; Bezzon, Osvaldo Luiz; Lovato-Silva, Cláudia Helena; Pagnano, Valéria Oliveira; Paranhos, Helena de Freitas Oliveira

    2012-01-01

    Chemical disinfectants are usually associated with mechanical methods to remove stains and reduce biofilm formation. This study evaluated the effect of disinfectants on release of metal ions and surface roughness of commercially pure titanium, metal alloys, and heat-polymerized acrylic resin, simulating 180 immersion trials. Disk-shaped specimens were fabricated with commercially pure titanium (Tritan), nickel-chromium-molybdenum-titanium (Vi-Star), nickel-chromium (Fit Cast-SB Plus), and nickel-chromium-beryllium (Fit Cast-V) alloys. Each cast disk was invested in the flasks, incorporating the metal disk to the heat-polymerized acrylic resin. The specimens (n=5) were immersed in these solutions: sodium hypochlorite 0.05%, Periogard, Cepacol, Corega Tabs, Medical Interporous, and Polident. Deionized water was used as a control. The quantitative analysis of metal ion release was performed using inductively coupled plasma mass spectrometry (ELAN DRC II). A surface analyzer (Surftest SJ-201P) was used to measure the surface roughness (µm). Data were recorded before and after the immersions and evaluated by two-way ANOVA and Tukey's test (α=0.05). The nickel release proved most significant with the Vi-Star and Fit Cast-V alloys after immersion in Medical Interporous. There was a significant difference in surface roughness of the resin (p=0.011) after immersion. Cepacol caused significantly higher resin roughness. The immersion products had no influence on metal roughness (p=0.388). It could be concluded that the tested alloys can be considered safe for removable denture fabrication, but disinfectant solutions as Cepacol and Medical Interporous tablet for daily denture immersion should be used with caution because it caused greater resin surface roughness and greater ion release, respectively.

  5. Ion energy distribution near a plasma meniscus with beam extraction for multi element focused ion beams

    SciTech Connect

    Mathew, Jose V.; Paul, Samit; Bhattacharjee, Sudeep

    2010-05-15

    An earlier study of the axial ion energy distribution in the extraction region (plasma meniscus) of a compact microwave plasma ion source showed that the axial ion energy spread near the meniscus is small ({approx}5 eV) and comparable to that of a liquid metal ion source, making it a promising candidate for focused ion beam (FIB) applications [J. V. Mathew and S. Bhattacharjee, J. Appl. Phys. 105, 96101 (2009)]. In the present work we have investigated the radial ion energy distribution (IED) under the influence of beam extraction. Initially a single Einzel lens system has been used for beam extraction with potentials up to -6 kV for obtaining parallel beams. In situ measurements of IED with extraction voltages upto -5 kV indicates that beam extraction has a weak influence on the energy spread ({+-}0.5 eV) which is of significance from the point of view of FIB applications. It is found that by reducing the geometrical acceptance angle at the ion energy analyzer probe, close to unidirectional distribution can be obtained with a spread that is smaller by at least 1 eV.

  6. Assessment of trace element impacts on agricultural use of water from the Dan River following the Eden coal ash release.

    PubMed

    Hesterberg, Dean; Polizzotto, Matthew L; Crozier, Carl; Austin, Robert E

    2016-04-01

    Catastrophic events require rapid, scientifically sound decision making to mitigate impacts on human welfare and the environment. The objective of this study was to analyze potential impacts of coal ash-derived trace elements on agriculture following a 35,000-tonne release of coal ash into the Dan River at the Duke Energy Steam Station in Eden, North Carolina. We performed scenario calculations to assess the potential for excessive trace element loading to soils via irrigation and flooding with Dan River water, uptake of trace elements by crops, and livestock consumption of trace elements via drinking water. Concentrations of 13 trace elements measured in Dan River water samples within 4 km of the release site declined sharply after the release and were equivalent within 5 d to measurements taken upriver. Mass-balance calculations based on estimates of soil trace-element concentrations and the nominal river water concentrations indicated that irrigation or flooding with 25 cm of Dan River water would increase soil concentrations of all trace elements by less than 0.5%. Calculations of potential increases of trace elements in corn grain and silage, fescue, and tobacco leaves suggested that As, Cr, Se, Sr, and V were elements of most concern. Concentrations of trace elements measured in river water following the ash release never exceeded adopted standards for livestock drinking water. Based on our analyses, we present guidelines for safe usage of Dan River water to diminish negative impacts of trace elements on soils and crop production. In general, the approach we describe here may serve as a basis for rapid assessment of environmental and agricultural risks associated with any similar types of releases that arise in the future.

  7. Adsorption of inorganic and organic ions to polycarbophil as a means of sustained-release dosage formulation.

    PubMed

    See, N A; Russell, J; Connors, K A; Bass, P

    1987-06-01

    The adsorption and desorption of drugs and inorganic ions to and from polycarbophil (PC), a polymer, were investigated to determine if PC would be a suitable carrier for sustained-release dosage formulations. Both in vitro and in vivo experiments with a polycarbophil-atropine sulfate complex demonstrated the gradual-release properties of this system. Adsorbed Cr3+ ions, like atropine, are released slowly. In contrast, 51CrO4(2-) ions are predominantly bound in an irreversible manner. A third group of drugs minimally adsorbed to PC under the conditions studied. We conclude that PC under both in vitro and in vivo conditions is able to bind certain ions and drugs and then release them over a period of time in a predictable and repeatable manner.

  8. Enhanced Ag(+) Ion Release from Aqueous Nanosilver Suspensions by Absorption of Ambient CO2.

    PubMed

    Fujiwara, Kakeru; Sotiriou, Georgios A; Pratsinis, Sotiris E

    2015-05-19

    Nanosilver with closely controlled average particle diameter (7-30 nm) immobilized on nanosilica is prepared and characterized by X-ray diffraction, N2 adsorption, and transmission electron microscopy. The presence of Ag2O on the as-prepared nanosilver surface is confirmed by UV-vis spectroscopy and quantified by thermogravimetric analysis and mass spectrometry. The release of Ag(+) ions in deionized water is monitored electrochemically and traced quantitatively to the dissolution of a preexisting Ag2O monolayer on the nanosilver surface. During this dissolution, the pH of the host solution rapidly increases, suppressing dissolution of the remaining metallic Ag. When, however, a nanosilver suspension is exposed to a CO2-containing atmosphere, like ambient air during its storage or usage, then CO2 is absorbed by the host solution decreasing its pH and contributing to metallic Ag dissolution and further leaching of Ag(+) ions. So the release of Ag(+) ions from the above closely sized nanosilver solutions in the absence and presence of CO2 as well as under synthetic air containing 200-1800 ppm of CO2 is investigated along with the solution pH and related to the antibacterial activity of nanosilver.

  9. Sustained release of antibiotic complexed by multivalent ion: in vitro and in vivo study for the treatment of peritonitis.

    PubMed

    Na, Seung Yeon; Oh, Se Heang; Kim, Tae Ho; Yoon, Jin A; Lee, In Soo; Lee, Jin Ho

    2014-12-10

    The main aims of this study are (i) the development of an antibiotic complexed with multivalent ion, which can allow sustained release of the antibiotic without any additional matrix or difficult process and (ii) the feasibility study of the ion-complexed antibiotic as a therapeutic technique for peritonitis treatment. An ion-complexed antibiotic is prepared by simple mixing of two aqueous solutions containing an ionized (water-soluble) drug (tetracycline) and a multivalent counter ionic compound. The ion-complexed antibiotic shows a continuous release of the antibiotic up to 21 days, and thus prolonged anti-bacterial effect by gradual ionic exchange between the multivalent ions in the complex and same-charged monovalent ions in surrounding medium. From the in vivo animal study using a cecum perforated peritonitis mouse model, the ion-complexed antibiotic group shows sufficient anti-bacterial effect and thus effectively treat the peritonitis because of the extermination of the contaminated enteric bacteria in the peritoneum during wound healing of injury cecum (by the sustained release of antibiotic from the ion complex). These results suggest that the ion-complexed antibiotic system may be promising for the effective treatment of the peritonitis caused by frequent gastrointestinal defect in clinical fields.

  10. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

    PubMed

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

  11. Temperature and Carbonate Ion Effects on Elemental Ratios in Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Jordan, K. A.; Rosenthal, Y.; Lear, C. H.; Keigwin, L.; Sikes, E. L.

    2006-12-01

    We have assessed temperature and carbonate ion effects on elemental ratios in benthic foraminifera using core top samples from Atlantic (Cape Hatteras Continental Shelf (CHCS) and Norwegian Sea) and Pacific (Indonesia, Hawaii, and New Zealand) depth transects. Our previous studies, based on comparing samples from Little Bahama Banks (LBB), Hawaii, and Indonesia (e.g., Rosenthal et al., 2005, 2006) have shown a significant difference in Mg/Ca ratios of calcitic species (Cibicidoides) and Mg/Ca and Sr/Ca of aragonitic species (Hoeglundina elegans) between sites characterized by the same temperature but different carbonate ion content, thereby suggesting that both variables influence the Mg/Ca and Sr/Ca composition of the foraminifera. It appears, however, that the major difference in these elemental ratios is between the LBB site and all other sites, rather than between the Atlantic and Pacific. The new results from the Atlantic suggest that foraminifera from the LBB transect may be compromised by diagenetic processes, and the carbonate ion effect is substantially smaller than previously thought. This conclusion, based on inter-basinal comparison, is consistent with our data from the homothermal, homosaline Norwegian Sea depth transect, which suggest minimal carbonate ion effect on Mg/Ca in calcitic benthic foraminifera. These data allow us to refine the Mg/Ca-temperature calibration for benthic species and assess temperature and carbonate ion effects on other trace elements (e.g., Li/Ca, B/Ca) under variable oceanographic conditions.

  12. Effect of glass composition on the degradation properties and ion release characteristics of phosphate glass--polycaprolactone composites.

    PubMed

    Prabhakar, Roopa L; Brocchini, Steve; Knowles, Jonathan C

    2005-05-01

    A series of polycaprolactone and ternary-based (Na(2)O)(0.55-x)(CaO)(x)(P(2)O(5))(0.45) glass composites were created, each containing 20% volume percentage of glass with various calcium compositions. A short-term degradation study was carried out to investigate the physical and ion release behaviour of these composites, utilising analytical techniques such as dynamical mechanical analysis, and ion chromatography. All the composites experienced significant loss of weight and stiffness throughout the study, with the 24 mol% calcium composites losing the greatest amount of weight and stiffness. The pH profile of the aqueous solutions in which the composites were placed were initially acidic, but began to neutralise mid-way through the study, with the 36 mol% solution achieving the most acidic conditions. The ion release behaviour mirrored the mass loss behaviour of the glass component of the composites. The cations (sodium and calcium ions) release was comparable with the initial stages of composite mass degradation, both of which exhibited almost immediate release when placed into solution. The 24 mol% composites underwent rapid rates of cation release, while the 36 mol% experienced the slowest rates of release. By contrast, anion (phosphates and polyphosphates) release showed a dissimilar trend, with rapid release of the P(2)O(7) and P(3)O(10) occurring during the first few hours in solution, whilst the P(3)O(9) structure released steadily during the first 48 h in solution. Finally, PO(4) release was at a constant rate over the duration of the study, releasing up to 300 ppm from the 32 and 36 mol% samples by the end of 200 h. To summarise, these results show that by combining phosphate glasses with biodegradable polymer, it is possible to create composites whose rate of degradation can be controlled to meet the needs of their end application.

  13. In vitro release of cupric ion from intrauterine devices: influence of frame, shape, copper surface area and indomethacin.

    PubMed

    Zhang, Shuangshuang; Li, Ying; Yu, Panpan; Chen, Tong; Zhou, Weisai; Zhang, Wenli; Liu, Jianping

    2015-02-01

    The release of cupric ion from copper intrauterine device (Cu-IUD) in human uterus is essential for contraception. However, excessive cupric ion will cause cytotoxic effect. In this paper, we investigated the influence of device characteristics (frame, copper surface area, shape, copper type and indomethacin) on copper release for the efficacy and adverse effects vary with IUD types which may correlate to their different release behaviors. Nine types of Cu-IUDs were selected and incubated in simulated uterine fluid. They were paired for comparison based on the device properties and the release of cupric ion was determined by flame atomic absorption spectrometer for about 160 days. The result showed that there was a burst release during the first month and the release rate tends to slow down and become steady afterwards. In addition, the copper release was mainly influenced by frame, indomethacin and copper type (copper wire and copper sleeve) while the shape variation had little effect on copper release throughout the experiment. Moreover, the influence of copper surface area was only noticeable during the first month. These findings were seldom reported before and may provide some useful information for the design of Cu-IUDs.

  14. Fabrication of porous zeolite/chitosan monoliths and their applications for drug release and metal ions adsorption.

    PubMed

    Zhang, Yongli; Yan, Weiwei; Sun, Zhiming; Pan, Cheng; Mi, Xue; Zhao, Gang; Gao, Jianping

    2015-03-06

    Ordered porous zeolite/chitosan (Zel/Chi) monoliths were prepared by a unidirectional freeze-drying method, and their properties and structures were characterized by various instrumental methods. The metal ion adsorption and the drug release performance of the porous Zel/Chi monoliths were also studied. The release rate of cefalexin from drug-loaded Zel/Chi monoliths depended on the composition and porous structure of the monoliths. The metal ion adsorption capacity of the Zel/Chi monoliths was related to the concentration of the metal ions, the adsorption time and the Zel/Chi ratio. An experimentally maximum adsorption of 89 mg/g was achieved for Cu(2+) ions. The Zel/Chi monoliths with adsorbed Cu(2+) ions effectively catalyzed the reduction of 4-nitrophenol to 4-aminophenol and had good recyclability. They were easily recovered by simply removing them from the reaction system and rinsing them with water.

  15. Hydrocolloid-based nutraceutical delivery systems: Effect of counter-ions on the encapsulation and release

    PubMed Central

    Polowsky, Patrick J.; Janaswamy, Srinivas

    2014-01-01

    Nutraceuticals provide health benefits, especially for the prevention and treatment of chronic diseases such as diabetes, obesity, cardiovascular disease and cancer. Their incorporation in food supplements, functional foods and medicinal foods is a major technological challenge due to lower water solubility, instability during processing and storage conditions. Carriers that can effectively overcome these predicaments and protect them during product development, consumption and delivery are in high demand. Toward this end, our research approach is to entrap nutraceuticals in the ordered networks of hydrocolloids. We have examined the effect cations in regulating the encapsulated amounts and release characteristics. Iota-carrageenan and eugenol have been chosen as models of hydrocolloid and nutraceutical, respectively, in the presence of Na and Ca ions. The results suggest that carrageenan maintains its network organization even after encapsulating the eugenol molecules. Increased eugenol amounts are found in the Na carrageenan complex compared to the Ca complex, and the release rate is faster from the former but it is more controlled from the latter. These differences highlight the vital role of cations on the encapsulation efficiency and release profiles of hydrocolloid-based nutraceutical carriers. The outcome offers an elegant opportunity for developing novel and value-added food systems employing low-in-cost, nontoxic and heavily consumed food grade hydrocolloids. PMID:25419030

  16. Ion-polycyclic aromatic hydrocarbon collisions: kinetic energy releases for specific fragmentation channels

    NASA Astrophysics Data System (ADS)

    Reitsma, G.; Zettergren, H.; Boschman, L.; Bodewits, E.; Hoekstra, R.; Schlathölter, T.

    2013-12-01

    We report on 30 keV He2 + collisions with naphthalene (C10H8) molecules, which leads to very extensive fragmentation. To unravel such complex fragmentation patterns, we designed and constructed an experimental setup, which allows for the determination of the full momentum vector by measuring charged collision products in coincidence in a recoil ion momentum spectrometer type of detection scheme. The determination of fragment kinetic energies is found to be considerably more accurate than for the case of mere coincidence time-of-flight spectrometers. In fission reactions involving two cationic fragments, typically kinetic energy releases of 2-3 eV are observed. The results are interpreted by means of density functional theory calculations of the reverse barriers. It is concluded that naphthalene fragmentation by collisions with keV ions clearly is much more violent than the corresponding photofragmentation with energetic photons. The ion-induced naphthalene fragmentation provides a feedstock of various small hydrocarbonic species of different charge states and kinetic energy, which could influence several molecule formation processes in the cold interstellar medium and facilitates growth of small hydrocarbon species on pre-existing polycyclic aromatic hydrocarbons.

  17. f-Element Ion Chelation in Highly Basic Media - Final Report

    SciTech Connect

    Paine, R.T.

    2000-12-12

    A large body of data has been collected over the last fifty years on the chemical behavior of f-element ions. The ions undergo rapid hydrolysis reactions in neutral or basic aqueous solutions that produce poorly understood oxide-hydroxide species; therefore, most of the fundamental f-element solution chemistry has allowed synthetic and separations chemists to rationally design advanced organic chelating ligands useful for highly selective partitioning and separation of f-element ions from complex acidic solution matrices. These ligands and new examples under development allow for the safe use and treatment of solutions containing highly radioactive species. This DOE/EMSP project was undertaken to address the following fundamental objectives: (1) study the chemical speciation of Sr and lanthanide (Ln) ions in basic aqueous media containing classical counter anions found in waste matrices; (2) prepare pyridine N-oxide phosphonates and phosphonic acids that might act as selective chelator s for Ln ions in model basic pH waste streams; (3) study the binding of the new chelators toward Ln ions and (4) examine the utility of the chelators as decontamination and dissolution agents under basic solution conditions. The project has been successful in attacking selected aspects of the very difficult problems associated with basic pH solution f-element waste chemistry. In particular, the project has (1) shed additional light on the initial stages of Ln ion sol-gel-precipitate formulation under basic solution conditions; (2) generated new families of pyridine phosphonic acid chelators; (3) characterized the function of the chelators and (4) examined their utility as oxide-hydroxide dissolution agents. These findings have contributed significantly to an improved understanding of the behavior of Ln ions in basic media containing anions found in typical waste sludges as well as to the development of sludge dissolution agents. The new chelating reagents are easily made and could be

  18. Simultaneous hydrogen and heavier element isotopic ratio images with a scanning submicron ion probe and mass resolved polyatomic ions.

    PubMed

    Slodzian, Georges; Wu, Ting-Di; Bardin, Noémie; Duprat, Jean; Engrand, Cécile; Guerquin-Kern, Jean-Luc

    2014-04-01

    In situ microanalysis of solid samples is often performed using secondary ion mass spectrometry (SIMS) with a submicron ion probe. The destructive nature of the method makes it mandatory to prevent information loss by using instruments combining efficient collection of secondary ions and a mass spectrometer with parallel detection capabilities. The NanoSIMS meets those requirements with a magnetic spectrometer but its mass selectivity has to be improved for accessing opportunities expected from polyatomic secondary ions. We show here that it is possible to perform D/H ratio measurement images using 12CD-/12CH-, 16OD-/16OH-, or 12C2D-/12C2H- ratios. These polyatomic species allow simultaneous recording of D/H ratios and isotopic compositions of heavier elements like 15N/14N (via 12C15N-/12C14N-) and they provide a powerful tool to select the phase of interest (e.g., mineral versus organics). We present high mass resolution spectra and an example of isotopic imaging where D/H ratios were obtained via the 12C2D-/12C2H- ratio with 12C2D- free from neighboring mass interferences. Using an advanced mass resolution protocol, a "conventional" mass resolving power of 25,000 can be achieved. Those results open many perspectives for isotopic imaging at a fine scale in biology, material science, geochemistry, and cosmochemistry.

  19. Metal ion-assisted self-assembly of complexes for controlled and sustained release of minocycline for biomedical applications.

    PubMed

    Zhang, Zhiling; Wang, Zhicheng; Nong, Jia; Nix, Camilla A; Ji, Hai-Feng; Zhong, Yinghui

    2015-01-20

    This study reports the development of novel drug delivery complexes self-assembled by divalent metal ion-assisted coacervation for controlled and sustained release of a hydrophilic small drug molecule minocycline hydrochloride (MH). MH is a multifaceted agent that has demonstrated therapeutic effects in infection, inflammation, tumor, as well as cardiovascular, renal, and neurological disorders due to its anti-microbial, anti-inflammatory, and cytoprotective properties. However, the inability to translate the high doses used in experimental animals to tolerable doses in human patients limits its clinical application. Localized delivery can potentially expose the diseased tissue to high concentrations of MH that systemic delivery cannot achieve, while minimizing the side effects from systemic exposure. The strong metal ion binding-assisted interaction enabled high drug entrapment and loading efficiency, and stable long term release for more than 71 d. Released MH demonstrated potent anti-biofilm, anti-inflammatory, and neuroprotective activities. Furthermore, MH release from the complexes is pH-sensitive as the chelation between minocycline and metal ions decreases with pH, allowing 'smart' drug release in response to the severity of pathology-induced tissue acidosis. This novel metal ion binding-mediated drug delivery mechanism can potentially be applied to other drugs that have high binding affinity for metal ions and may lead to the development of new delivery systems for a variety of drugs.

  20. Exposure of Cleft Lip and Palate Patients to Toxic Elements Released during Orthodontic Treatment in the Study of Non-Invasive Matrices

    PubMed Central

    Mikulewicz, Marcin; Kachniarz, Krzysztof; Chojnacka, Katarzyna

    2015-01-01

    The Objective The aim of the study was evaluation of metal ions (nickel and chromium) released from orthodontic appliances in cleft lip and palate patients and the usefulness of non-invasive matrices (saliva and hair). Materials and Methods The material studied consisted of 100 individuals, including 59 females and 41 males of 5 to 16 years of age, which were divided into 3 groups: experimental–patients with cleft lip and palate (36 individuals, the average treatment time 5.74 years); control group–patients without cleft lip and palate, during orthodontic treatment (32 individuals, the average treatment time 1.78 years) and the control group patients without cleft lip and palate, without any orthodontic appliances (32 individuals). Samples (saliva, hair) were collected and subjects underwent a survey by questionnaire. Multi-elemental analyses of the composition of non-invasive matrices was conducted in an accredited laboratory by inductively coupled plasma spectrometry technique ICP-OES. The results were reported as mean contents of particular elements (Cd, Cr, Cu, Fe, Mn, Mo, Ni, Si) in hair and in saliva. Results The concentration of Cr, Ni, Fe and Cu ions in saliva of cleft lip and palate patients were several times higher as compared with not treated orthodontically control groups and higher than in the group with orthodontic appliances. Among the assessed matrices, hair of cleft lip and palate patients seem to be not a meaningful biomarker. Conclusion It was found that orthodontic appliances used in long-term treatment of cleft lip and palate patients do not release toxic levels of Cr and Ni ions. PMID:26544176

  1. Fabricating high-density magnetic storage elements by low-dose ion beam irradiation

    SciTech Connect

    Neb, R.; Sebastian, T.; Pirro, P.; Hillebrands, B.; Pofahl, S.; Schaefer, R.; Reuscher, B.

    2012-09-10

    We fabricate magnetic storage elements by irradiating an antiferromagnetically coupled ferromagnetic/nonmagnetic/ferromagnetic trilayer by a low-dose ion beam. The irradiated areas become ferromagnetically coupled and are capable of storing information if their size is small enough. We employ Fe/Cr/Fe trilayers and a 30 keV focused Ga{sup +}-ion beam to demonstrate the working principle for a storage array with a bit density of 7 Gbit/in.{sup 2}. Micromagnetic simulations suggest that bit densities of at least two magnitudes of order larger should be possible.

  2. Influence of drug distribution and solubility on release from geopolymer pellets--a finite element method study.

    PubMed

    Jämstorp, Erik; Strømme, Maria; Bredenberg, Susanne

    2012-05-01

    This study investigates the influence of drug solubility and distribution on its release from inert geopolymer pellets of three different sizes (1.5 × 1.5, 3 × 6, and 6 × 6 mm), having the same geopolymer composition and containing highly potent opioid fentanyl, sumatriptan, theophylline, or saccharin. Scanning electron microscopy, nitrogen sorption, drug solubility, permeation, and release experiments were performed, and estimates of the drug diffusion coefficients and solubilities in the geopolymer matrix were derived with the aid of finite element method (FEM). FEM was further employed to investigate the effect of a nonuniform drug distribution on the drug release profile. When inspecting the release profiles for each drug, it was observed that their solubilities in the geopolymer matrix imposed a much greater influence on the drug release rate than their diffusion coefficients. Concentrating the initial drug load in FEM into nonuniformly distributed drug regions inside the matrix created drug release profiles that more closely resembled experimental data than an FEM-simulated uniform drug distribution did. The presented FEM simulations and visualization of drug release from geopolymers under varying initial and dynamic conditions should open up for more systematic studies of additional factors that influence the drug release profile from porous delivery vehicles.

  3. Regulation of renin release by calcium and ammonium ions in normal man.

    PubMed

    Kisch, E S; Dluhy, R G; Williams, G H

    1976-12-01

    The effect of infusing calcium chloride, magnesium sulfate, sodium lactate, and ammonium chloride on renin secretion was compared to equimolar infusions of hypotonic and normal saline in sodium-deplete normal subjects. The infusion of 75 mEq of ammonium chloride for 60 min in 6 normal, sodium-deplete subjects suppressed plasma renin activity significantly (P less than 0.01) from 4.4 +/- 0.8 to 2.1 +/- 0.2 ng/ml/h, an effect comparable to that produced by normal saline. Sodium lactate (75 mEq sodium/hr) also significantly reduced renin levels at 20-30 min (P less than 0.01). The infusion of 1/3 normal saline (25 mEq sodium/h for 2 h) produced a significant reduction (P less than 0.01) in plasma renin activity (from control levels of 5.2 +/- 0.8 to 3.1 +/- 0.6 ng/ml/h at 90 min). On the other hand, comparable infusions of 50 mEq of magnesium sulfate over 2 h had no effect on renin release (4.6 +/- 0.8 to 4.6 +/- 0.9 ng/ml/h at 2 h), while the infusion of calcium chloride produced an intermediate reduction (5.2 +/- 1.2 to 3.7 +/- 0.8 ng/ml/h at 2 h (P less than 0.05). The observed effects of the hydrogen and calcium ions on suppressing renin release may be secondary to their known actions on renal sodium excretion. Since the infusions of calcium and hydrogen ions both result in an increased delivery of sodium to the distal segment of the nephron, the results may reflect the regulation of renin by the macula densa, a sensitive intrarenal sensor of renal tubular sodium.

  4. CASCADES AFTER K-VACANCY PRODUCTION IN ATOMS AND IONS OF LIGHT ELEMENTS

    SciTech Connect

    Kucas, S.; Karazija, R.; Momkauskaite, A.

    2012-05-10

    The results of detailed level-by-level calculations of Auger and radiative cascades after K-vacancy production are presented for the astrophysically important elements, namely Ne, Mg, Si, S, and Ar. Calculations are performed using the single-configuration, quasi-relativistic approximation. The whole isonuclear sequence of ions for a given element is considered. For the first time, the dependence of the cascade on the initial vacancy state is investigated. The populations are presented not only for the levels of the final configurations, but also for the levels of the excited configurations after the Auger transitions. An intense characteristic emission can be observed from such levels.

  5. Nonlinear ion-acoustic waves in a degenerate plasma with nuclei of heavy elements

    SciTech Connect

    Hossen, M. A. Mamun, A. A.

    2015-10-15

    The ion-acoustic (IA) solitary waves propagating in a fully relativistic degenerate dense plasma (containing relativistic degenerate electron and ion fluids, and immobile nuclei of heavy elements) have been theoretically investigated. The relativistic hydrodynamic model is used to derive the Korteweg-de Vries (K-dV) equation by the reductive perturbation method. The stationary solitary wave solution of this K-dV equation is obtained to characterize the basic features of the IA solitary structures that are found to exist in such a degenerate plasma. It is found that the effects of electron dynamics, relativistic degeneracy of the plasma fluids, stationary nuclei of heavy elements, etc., significantly modify the basic properties of the IA solitary structures. The implications of this results in astrophysical compact objects like white dwarfs are briefly discussed.

  6. Loading and release of amine drugs by ion-exchange fibers: role of amine type.

    PubMed

    Gao, Yanan; Liu, Hongzhuo; Yuan, Jing; Yang, Yang; Che, Xin; Hou, Yanlong; Li, Sanming

    2014-04-01

    With more production and application of ion-exchange fibers (IEFs), it becomes necessary to understand the interaction between IEFs and amine compounds, an important group of organic drugs and structural components of large organic molecules in biological systems. However, so far few experimental studies have been conducted to systematically investigate the exchanging mechanism of amine compounds to IEFs. Therefore, 15 amine drugs were selected to investigate the effect of amine type on the loading and release of them from the related IEFs. Loading affinity of these drugs by IEFs decreased in the order of secondary, tertiary, and primary. The following items: basicity, aromaticity, molar volume, rotatability, and so on, were emphatically discussed to address the underlying mechanism of drug loading and releasing extent and rate of IEFs. It was evident that strong alkaline drugs strengthened the ionic bond between the amine groups and IEFs, and thus the loading affinity. These results will advance the understanding of the exchanging behavior of IEFs in the drug delivery system.

  7. The Antimicrobial Properties of Silver Nanoparticles in Bacillus subtilis Are Mediated by Released Ag+ Ions

    PubMed Central

    Hsueh, Yi-Huang; Lin, Kuen-Song; Ke, Wan-Ju; Hsieh, Chien-Te; Chiang, Chao-Lung; Tzou, Dong-Ying; Liu, Shih-Tung

    2015-01-01

    The superior antimicrobial properties of silver nanoparticles (Ag NPs) are well-documented, but the exact mechanisms underlying Ag-NP microbial toxicity remain the subject of intense debate. Here, we show that Ag-NP concentrations as low as 10 ppm exert significant toxicity against Bacillus subtilis, a beneficial bacterium ubiquitous in the soil. Growth arrest and chromosomal DNA degradation were observed, and flow cytometric quantification of propidium iodide (PI) staining also revealed that Ag-NP concentrations of 25 ppm and above increased membrane permeability. RedoxSensor content analysis and Phag-GFP expression analysis further indicated that reductase activity and cytosolic protein expression decreased in B. subtilis cells treated with 10–50 ppm of Ag NPs. We conducted X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses to directly clarify the valence and fine structure of Ag atoms in B. subtilis cells placed in contact with Ag NPs. The results confirmed the Ag species in Ag NP-treated B. subtilis cells as Ag2O, indicating that Ag-NP toxicity is likely mediated by released Ag+ ions from Ag NPs, which penetrate bacterial cells and are subsequently oxidized intracellularly to Ag2O. These findings provide conclusive evidence for the role of Ag+ ions in Ag-NP microbial toxicity, and suggest that the impact of inappropriately disposed Ag NPs to soil and water ecosystems may warrant further investigation. PMID:26669836

  8. Mass analysis of neutral particles and ions released during electrical breakdowns on spacecraft surfaces

    NASA Technical Reports Server (NTRS)

    Kendall, B. R. F.

    1985-01-01

    Charged-particle fluxes from breakdown events were studied. Methods to measure mass spectra and total emitted flux of neutral particles were developed. The design and construction of the specialized mass spectrometer was completed. Electrical breakdowns were initiated by a movable blunt contact touching the insulating surface. The contact discharge apparatus was used for final development of two different high-speed recording systems and for measurements of the composition of the materials given off by the discharge. It was shown that intense instantaneous fluxes of neutral particles were released from the sites of electrical breakdown events. A laser micropulse mass analyzer showed that visible discoloration at breakdown sites were correllated with the presence of iron on the polymer side of the film, presumably caused by punch-through to the Inconel backing. Kapton samples irradiated by an oxygen ion beam were tested. The irradiated samples were free of surface hydrocarbon contamination but otherwise behaved in the same way as the Kapton samples tested earlier. Only the two samples exposed to oxygen ion bombardment were relatively clean. This indicates an additional variable that should be considered when testing spacecraft materials in the laboratory.

  9. Special diffractive elements for optical trapping fabricated on optical fiber tips using the focused ion beam

    NASA Astrophysics Data System (ADS)

    Rodrigues Ribeiro, R. S.; Guerreiro, A.; Viegas, J.; Jorge, P. A. S.

    2016-05-01

    In this work, spiral phase lenses and Fresnel zone lenses for beam tailoring, fabricated on the tip of optical fibers, are reported. The spiral phase lenses allow tailoring the fundamental guided mode, a Gaussian beam, into a Laguerre - Gaussian profile without using additional optical elements. Whereas, the Fresnel lenses are used as focusing systems. The lenses are fabricated using Focused Ion Beam milling, enabling high resolution in the manufacturing process. The output optical intensity profiles matching the numerical simulations are presented and analyzed.

  10. Photo-controlled metal-ion (Zn2+ and Cd2+) release in aqueous Tween-20 micelle solution.

    PubMed

    Zhang, Xu; Chen, Yi

    2012-02-21

    Photo-controlled metal-ion (Zn(2+) and Cd(2+)) release in aqueous micelle solution (tris-HCl, pH = 7.4) has been described using 2-((2-mercaptophenylimino)methyl) phenol as ligand. It is found that both the ligand-Zn complex (1) and the ligand-Cd complex (2) are stable in micelle solution, and Zn(2+) (Cd(2+)) can be released from the complex with 365 nm light trigger. Accompanying the metal-ion release, the ligand is photo-converted to 2-(benzothiazol-2-yl) phenol (3) as product, and the turn-on fluorescence is detected. The fluorescence intensity increases with the photo-triggered release until Zn(2+) (Cd(2+)) is completely released, which is beneficial for monitoring the process of photo-controlled metal ion release. Control experiments demonstrate that no binding occurs between 3 and Zn(2+) (Cd(2+)) in micelle solution and there is no binding between cations and micelle, either.

  11. An asymmetric approach to modeling ion channels using finite element analysis.

    PubMed

    Siksik, M; Krishnamurthy, V

    2009-01-01

    Biological ion channels are water filled pores in the cell membrane. They regulate the flow of ions in and out of the cell. Modeling the dynamics of these channels and relating their structure to functionality is crucial in understanding the mechanisms by which they conduct. This paper proposes a novel Finite Element Method (FEM) based simulation framework for modeling of ion channels that does not assume channel symmetry. This is the first framework that allows the use of multiple dielectric constants inside such channels without assuming geometrical symmetry thus providing a more realistic model of the channel. Due to the run-time complexity of the problem, lookup tables must be constructed in memory to store pre-calculated electric potential information. The large number of elements involved in FEM and channel resolution requirements can potentially result in very large lookup tables leading to a performance "bottleneck". This paper answers the following question: Does the accuracy introduced by using an asymmetric model outweigh the inaccuracy caused by having to reduce the size and resolution of electric-field look-up tables? This paper compares the memory footprint of an ion channel simulator that assumes a symmetric channel model versus an asymmetric model. We show that currently available personal computers are sufficient for attaining reasonable levels of accuracy for both. Our results show diminishing returns in accuracy with tables sized greater than 8.5 GB for the asymmetric model.

  12. Nanometer scale elemental analysis in the helium ion microscope using time of flight spectrometry.

    PubMed

    Klingner, N; Heller, R; Hlawacek, G; von Borany, J; Notte, J; Huang, J; Facsko, S

    2016-03-01

    Time of flight backscattering spectrometry (ToF-BS) was successfully implemented in a helium ion microscope (HIM). Its integration introduces the ability to perform laterally resolved elemental analysis as well as elemental depth profiling on the nm scale. A lateral resolution of ≤54nm and a time resolution of Δt≤17ns(Δt/t≤5.4%) are achieved. By using the energy of the backscattered particles for contrast generation, we introduce a new imaging method to the HIM allowing direct elemental mapping as well as local spectrometry. In addition laterally resolved time of flight secondary ion mass spectrometry (ToF-SIMS) can be performed with the same setup. Time of flight is implemented by pulsing the primary ion beam. This is achieved in a cost effective and minimal invasive way that does not influence the high resolution capabilities of the microscope when operating in standard secondary electron (SE) imaging mode. This technique can thus be easily adapted to existing devices. The particular implementation of ToF-BS and ToF-SIMS techniques are described, results are presented and advantages, difficulties and limitations of this new techniques are discussed.

  13. Development of sustained release fast-disintegrating tablets using various polymer-coated ion-exchange resin complexes.

    PubMed

    Jeong, Seong Hoon; Park, Kinam

    2008-04-02

    Complex formation between drugs and ion-exchange resins was investigated and the effects of coating by various aqueous polymeric dispersions on the complexes were evaluated for developing new sustained-release fast-disintegrating tablets (FDTs). Complexes of ion-exchange resin and dextromethorphan, a model drug, were prepared using different particle sizes of the resins. Aqueous colloidal dispersions of ethylcellulose (EC) and poly(vinyl acetate) (Kollicoat SR30D) were used for fluid-bed coating. Based on drug loading, release profiles, and scanning electron microscopy (SEM) images, the coated particles were granulated with suitable tablet excipients and then compressed into the tablets. Drug release profiles and SEM pictures were compared before and after the manufacturing processes. As the particle size of resins increased, the drug loading and release rate decreased due to the reduced effective diffusion coefficient and surface area. Higher coating level decreased the release rate further. In contrast to EC, Kollicoat SR30D coated particles could be compressed into tablets without any rupture or cracks on the coating since the mechanical properties of the polymer was more resistant to the manufacturing processes. This resulted in no significant changes in release rates. SEM showed the mechanical strength of the polymers affected the morphological change after compression. When the drug release profiles were applied into Boyd model and Higuchi equation, the linear relationship was observed, indicating that the diffusion within the resin matrix is the rate-controlling step.

  14. Garnet/high-silica rhyolite trace element partition coefficients measured by ion microprobe

    USGS Publications Warehouse

    Sisson, T.W.; Bacon, C.R.

    1992-01-01

    Garnet/liquid trace element partition coefficients have been measured in situ by ion microprobe in a rhyolite from Monache Mountain, California. Partition coefficients are reported for La, Ce, Nd, Sm, Dy, Er, Yb, Sc, Ti, V, Cr, Sr, Y, and Zr. The in situ analyses avoid the problem of contamination of the garnet phase by trace element-rich accessory minerals encountered in traditional bulk phenocryst/matrix partitioning studies. The partitioning pattern for the rare earth elements (REEs, excluding Eu) is smooth and rises steeply from the light to the heavy REEs with no sharp kinks or changes in slope, unlike patterns for garnet /silicic liquid REE partitioning determined by bulk methods. This difference suggests that the previous determinations by bulk methods are in error, having suffered from contamination of the phenocryst separates. ?? 1992.

  15. Strain-energy-release rate analysis of the end-notched flexure specimen using the finite-element method

    NASA Technical Reports Server (NTRS)

    Salpekar, S. A.; Raju, I. S.; Obrien, T. K.

    1987-01-01

    Two-dimensional finite-element analysis of the end-notched flexure specimen was performed using 8-node isoparametric, parabolic elements to evaluate compliance and mode II strain energy release rates, G sub II. The G sub II values were computed using two different techniques: the virtural crack-closure technique (VCCT) and the rate of change of compliance with crack length (compliance derivative method). The analysis was performed for various crack-length-to-semi-span (a/L) ratios ranging from 0.2 to 0.9. Three material systems representing a wide range of material properties were analyzed. The compliance and strain energy release rates of the specimen calculated with the present finite-element analysis agree very well with beam theory equations including transverse shear. The G sub II values calculated using the compliance derivative method compared extremely well with those calculated using the VCCT. The G sub II values obtained by the compliance derivative method using the top or bottom beam deflections agreed closely with each other. The strain energy release rates from a plane-stress analysis were higher than the plane-strain values by only a small percentage, indicating that either assumption may be used in the analysis. The G sub II values for one material system calculated from the finite-element analysis agreed with one solution in the literature and disagreed with the other solution in the literature.

  16. Strain energy release rate analysis of the end-notched flexure specimen using the finite-element method

    NASA Technical Reports Server (NTRS)

    Salpekar, S. A.; Raju, I. S.; O'Brien, T. K.

    1988-01-01

    Two-dimensional finite-element analysis of the end-notched flexure specimen was performed using 8-node isoparametric, parabolic elements to evaluate compliance and mode II strain energy release rates, G sub II. The G sub II values were computed using two different techniques: the virtual crack-closure technique (VCCT) and the rate of change of compliance with crack length (compliance derivative method). The analysis was performed for various crack-length-to-semi-span (a/L) ratios ranging from 0.2 to 0.9. Three material systems representing a wide range of material properties were analyzed. The compliance and strain energy release rates of the specimen calculated with the present finite-element analysis agree very well with beam theory equations including transverse shear. The G sub II values calculated using the compliance derivative method compared extremely well with those calculated using the VCCT. The G sub II values obtained by the compliance derivative method using the top or bottom beam deflections agreed closely with each other. The strain energy release rates from a plane-stress analysis were higher than the plane-strain values by only a small percentage, indicating that either assumption may be used in the analysis. The G sub II values for one material system calculated from the finte-element analysis agreed with one solution in the literature and disagreed with the other solution in the literature.

  17. Stabilized finite element methods to simulate the conductances of ion channels

    NASA Astrophysics Data System (ADS)

    Tu, Bin; Xie, Yan; Zhang, Linbo; Lu, Benzhuo

    2015-03-01

    We have previously developed a finite element simulator, ichannel, to simulate ion transport through three-dimensional ion channel systems via solving the Poisson-Nernst-Planck equations (PNP) and Size-modified Poisson-Nernst-Planck equations (SMPNP), and succeeded in simulating some ion channel systems. However, the iterative solution between the coupled Poisson equation and the Nernst-Planck equations has difficulty converging for some large systems. One reason we found is that the NP equations are advection-dominated diffusion equations, which causes troubles in the usual FE solution. The stabilized schemes have been applied to compute fluids flow in various research fields. However, they have not been studied in the simulation of ion transport through three-dimensional models based on experimentally determined ion channel structures. In this paper, two stabilized techniques, the SUPG and the Pseudo Residual-Free Bubble function (PRFB) are introduced to enhance the numerical robustness and convergence performance of the finite element algorithm in ichannel. The conductances of the voltage dependent anion channel (VDAC) and the anthrax toxin protective antigen pore (PA) are simulated to validate the stabilization techniques. Those two stabilized schemes give reasonable results for the two proteins, with decent agreement with both experimental data and Brownian dynamics (BD) simulations. For a variety of numerical tests, it is found that the simulator effectively avoids previous numerical instability after introducing the stabilization methods. Comparison based on our test data set between the two stabilized schemes indicates both SUPG and PRFB have similar performance (the latter is slightly more accurate and stable), while SUPG is relatively more convenient to implement.

  18. Negligible particle-specific toxicity mechanism of silver nanoparticles: the role of Ag+ ion release in the cytosol.

    PubMed

    De Matteis, Valeria; Malvindi, Maria Ada; Galeone, Antonio; Brunetti, Virgilio; De Luca, Elisa; Kote, Sachin; Kshirsagar, Prakash; Sabella, Stefania; Bardi, Giuseppe; Pompa, Pier Paolo

    2015-04-01

    Toxicity of silver nanoparticles (AgNPs) is supported by many observations in literature, but no mechanism details have been proved yet. Here we confirm and quantify the toxic potential of fully characterized AgNPs in HeLa and A549 cells. Notably, through a specific fluorescent probe, we demonstrate the intracellular release of Ag(+) ions in living cells after nanoparticle internalization, showing that in-situ particle degradation is promoted by the acidic lysosomal environment. The activation of metallothioneins in response to AgNPs and the possibility to reverse the main toxic pathway by Ag(+) chelating agents demonstrate a cause/effect relationship between ions and cell death. We propose that endocytosed AgNPs are degraded in the lysosomes and the release of Ag(+) ions in the cytosol induces cell damages, while ions released in the cell culture medium play a negligible effect. These findings will be useful to develop safer-by-design nanoparticles and proper regulatory guidelines of AgNPs. From the clinical editor: The authors describe the toxic potential of silver nanoparticles (AgNP) in human cancer cell lines. Cell death following the application of AgNPs is dose-dependent, and it is mostly due to Ag+ ions. Further in vivo studies should be performed to gain a comprehensive picture of AgNP-toxicity in mammals.

  19. The Release of Elements from the Base Metal Alloys in a Protein Containing Biologic Environments and Artificial Saliva – An Invitro Study

    PubMed Central

    Shetty, Manoj; Prasad, D Krishna; Kanathila, Hema

    2016-01-01

    Introduction It has been reported that protein containing solutions can accelerate the release of elements from the base metal alloys. Aim This study aims to determine whether the solution in which an alloy is submerged and the exposure time have any effect on the amount of release of elements from the Ni-Cr and Co-Cr alloys. Material and Methods A total of 126 specimens were made from the Ni-Cr alloy and 42 specimens were made from Co-Cr alloy in the form of 5mm diameter discs, 2mm in thickness. Dissolution experiments were carried out in Bovine Serum Albumin (BSA) and artificial saliva for a period of seven weeks and atomic absorption spectrophotometer was used for elemental analysis. Statistical Analysis T-test was done to correlate the difference of elemental release from both BSA and artificial saliva. ANOVA test was done to compare the release at different time intervals and to compare the release of elements at different time intervals within a particular solution. TUKEY HSD test was done for comparison between the elements in a particular solution. Results The results showed that the elemental release was seen in both the solutions with a significant increase of release in BSA. The release of elements from the Ni-Cr alloy showed the predominant release of Cr. Conclusion The protein containing solution showed maximum release of elements from Ni-Cr and Co-Cr alloys. The elements that released from the alloys never reached their threshold for toxic effects. Hence these alloys can be safely used in fabrication of metal restorations without any ill effects. PMID:26894170

  20. A New Radio Frequency Plasma Oxygen Primary Ion Source on Nano Secondary Ion Mass Spectrometry for Improved Lateral Resolution and Detection of Electropositive Elements at Single Cell Level.

    PubMed

    Malherbe, Julien; Penen, Florent; Isaure, Marie-Pierre; Frank, Julia; Hause, Gerd; Dobritzsch, Dirk; Gontier, Etienne; Horréard, François; Hillion, François; Schaumlöffel, Dirk

    2016-07-19

    An important application field of secondary ion mass spectrometry at the nanometer scale (NanoSIMS) is the detection of chemical elements and, in particular, metals at the subcellular level in biological samples. The detection of many trace metals requires an oxygen primary ion source to allow the generation of positive secondary ions with high yield in the NanoSIMS. The duoplasmatron oxygen source is commonly used in this ion microprobe but cannot achieve the same quality of images as the cesium primary ion source used to produce negative secondary ions (C(-), CN(-), S(-), P(-)) due to a larger primary ion beam size. In this paper, a new type of an oxygen ion source using a rf plasma is fitted and characterized on a NanoSIMS50L. The performances of this primary ion source in terms of current density and achievable lateral resolution have been characterized and compared to the conventional duoplasmatron and cesium sources. The new rf plasma oxygen source offered a net improvement in terms of primary beam current density compared to the commonly used duoplasmatron source, which resulted in higher ultimate lateral resolutions down to 37 nm and which provided a 5-45 times higher apparent sensitivity for electropositive elements. Other advantages include a better long-term stability and reduced maintenance. This new rf plasma oxygen primary ion source has been applied to the localization of essential macroelements and trace metals at basal levels in two biological models, cells of Chlamydomonas reinhardtii and Arabidopsis thaliana.

  1. Effect of weathering transformations of coal combustion residuals on trace elements mobility in view of the environmental safety and sustainability of their disposal and use. II. Element release.

    PubMed

    Stefaniak, Sebastian; Kmiecik, Ewa; Miszczak, Ewa; Szczepańska-Plewa, Jadwiga; Twardowska, Irena

    2015-06-01

    This paper is the second one of two companion papers. It presents results of a study aimed at assessing the effect of real time weathering transformations of Coal Combustion Residuals (CCRs) on trace element binding/release and its environmental implications. The study is based on the chemical composition of pore solutions extracted from primary alkaline Class F CCRs, 0 to >40 years old, sampled from the surface layer and vertical profiles at four selected typical CCRs impoundments. The long-term weathering transformations were found to lead to gradual acidification to pH < 4 of this primary alkaline material, due to internal processes of mineral formation/dissolution. Direct analysis of the pore solutions and a statistical analysis have shown different susceptibility of many trace elements to release during internal acidification processes occurring at consecutive Wash-out I (pH > 8), Dissolution II (8 ≥ pH ≥ 7) and Delayed Release III (pH < 7) stages of weathering compared to that at external sources of pH. The elements occurring in the CCRs are represented by three major groups showing the highest release to pore water: (a) within the acidic pH range (Na, K, Zn, Fe, Cd, Mo, Cr, B, Mn, Be and Ni; (b) within the near-neutral pH range (Al, V, Ba, Cu and Ag) and also Sb, Hg and Co not analyzed at pH < 7; (c) within the alkaline pH range (Ca, Mg, Pb, As, Se, Tl). Elements whose concentrations exceeded the threshold values for good chemical status of groundwater (TVs) at all weathering stages over the entire pH range studied were K, Al, B, Cr, Mo, V, As, Se, Sb and Hg, while Na, Zn, Fe and Cd showed particularly high delayed release at pH < 7, thus confirming the need of a precautionary approach to CCRs uncontrolled disposal and bulk reuse as common fill in view of long term environmental safety and sustainability.

  2. Light at the end of the Ca(2+)-release channel tunnel: structures and mechanisms involved in ion translocation in ryanodine receptor channels.

    PubMed

    Williams, A J; West, D J; Sitsapesan, R

    2001-02-01

    RyR and InsP3R are Ca(2+)-release channels. When induced to open by the appropriate stimulus, these channels allow Ca2+ to leave intracellular storage organelles at an astonishing rate. Investigations of the ion-handling properties of isolated RyR channels have demonstrated that, at least in comparison to voltage-gated channels of surface membranes, these channels display limited powers of discrimination between physiologically relevant cations and this relative lack of selectivity is likely to contribute to the ability of Ca(2+)-release channels to maintain high rates of cation translocation without compromising function. A range of ion-handling properties in RyR are consistent with the proposal that this channel functions as a single-ion channel and theoretical considerations indicate that the high rates of ion translocation monitored for RyR would require the pore of such a structure to be short and possess a large capture radius. Measurements of the dimensions of regions of RyR involved in ion conduction and discrimination indicate that this is likely to be the case. In each monomer of RyR/InsP3R, residues making up the last two trans-membrane spanning domains and a luminal loop linking these two helices contribute to the formation of the channel pore. The luminal loops of both RyR and InsP3R contain amino acid sequences similar to those known to form the selectivity filter of K+ channels. In addition the luminal loops of both Ca(2+)-release channels contain sequences that are likely to form helices that may be analogous to the pore helix visualised in KcsA. The correlation in structural elements of the luminal loops of RyR/InsP3R and KcsA has prompted us to speculate on the tertiary arrangement for this region of the Ca(2+)-release channels using the established structure of KcsA as a framework.

  3. Ion microprobe elemental analyses of impact features on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Hunter, Jerry L.; Wortman, Jim J.; Griffis, Dieter P.; Simon, Charles G.

    1991-01-01

    Hypervelocity impact features on several of the electro-active dust sensors utilized in the Interplanetary Dust Experiment (IDE) were subjected to elemental analysis using an ion microprobe. The negatively biased dust sensor surfaces acted as ion traps for cations produced in the plasma plumes of impacting particles. Impactor residue surrounds most impact features to two or three feature diameters. After etching away a layer of carbonaceous/silicaceous surface contamination, low mass resolution elemental survey scans are used to tentatively identify the presence of impactor debris. High mass resolution two-dimensional elemental maps and three dimensional depth profiling of the feature and surrounding area show the distribution and relative composition of the debris. The location of these sensors on the six primary Long Duration Exposure Facility (LDEF) sides provides a unique opportunity to further define the debris environment. Researchers applied the same techniques to impact and contaminant features on a set of ultra-pure, highly polished single crystal germanium wafer witness plates that were mounted on row 12 and exposed to the environment during the entire mission.

  4. Ion selectivity of porcine skeletal muscle Ca2+ release channels is unaffected by the Arg615 to Cys615 mutation.

    PubMed Central

    Shomer, N H; Mickelson, J R; Louis, C F

    1994-01-01

    The Arg615 to Cys615 mutation of the sarcoplasmic reticulum (SR) Ca2+ release channel of malignant hyperthermia susceptible (MHS) pigs results in a decreased sensitivity of the channel to inhibitory Ca2+ concentrations. To investigate whether this mutation also affects the ion selectivity filter of the channel, the monovalent cation conductances and ion permeability ratios of single Ca2+ release channels incorporated into planar lipid bilayers were compared. Monovalent cation conductances in symmetrical solutions were: Li+, 183 pS +/- 3 (n = 21); Na+, 474 pS +/- 6 (n = 29); K+, 771 pS +/- 7 (n = 29); Rb+, 502 pS +/- 10 (n = 22); and Cs+, 527 pS +/- 5 (n = 16). The single-channel conductances of MHS and normal Ca2+ release channel were not significantly different for any of the monovalent cations tested. Permeability ratios measured under biionic conditions had the permeability sequence Ca2+ >> Li+ > Na+ > K+ > or Rb+ > Cs+, with no significant difference noted between MHS and normal channels. This systematic examination of the conduction properties of the pig skeletal muscle Ca2+ release channel indicated a higher Ca2+ selectivity (PCa2+:Pk+ approximately 15.5) than the sixfold Ca2+ selectivity previously reported for rabbit skeletal (Smith et al., 1988) or sheep cardiac muscle (Tinker et al., 1992) Ca2+ release channels. These results also indicate that although Ca2+ regulation of Ca2+ release channel activity is altered, the Arg615 to Cys615 mutation of the porcine Ca2+ release channel does not affect the conductance or ion selectivity properties of the channel. PMID:7948678

  5. Finite element simulation of the gating mechanism of mechanosensitive ion channels

    NASA Astrophysics Data System (ADS)

    Bavi, Navid; Qin, Qinghua; Martinac, Boris

    2013-08-01

    In order to eliminate limitations of existing experimental or computational methods (such as patch-clamp technique or molecular dynamic analysis) a finite element (FE) model for multi length-scale and time-scale investigation on the gating mechanism of mechanosensitive (MS) ion channels has been established. Gating force value (from typical patch clamping values) needed to activate Prokaryotic MS ion channels was applied as tensional force to the FE model of the lipid bilayer. Making use of the FE results, we have discussed the effects of the geometrical and the material properties of the Escherichia coli MscL mechanosensitive ion channel opening in relation to the membrane's Young's modulus (which will vary depending on the cell type or cholesterol density in an artificial membrane surrounding the MscL ion channel). The FE model has shown that when the cell membrane stiffens the required channel activation force increases considerably. This is in agreement with experimental results taken from the literature. In addition, the present study quantifies the relationship between the membrane stress distribution around a `hole' for modeling purposes and the stress concentration in the place transmembrane proteins attached to the hole by applying an appropriate mesh refinement as well as well defining contact condition in these areas.

  6. Synthesis of large FeSe superconductor crystals via ion release/introduction and property characterization

    NASA Astrophysics Data System (ADS)

    Dongna, Yuan; Yulong, Huang; Shunli, Ni; Huaxue, Zhou; Yiyuan, Mao; Wei, Hu; Jie, Yuan; Kui, Jin; Guangming, Zhang; Xiaoli, Dong; Fang, Zhou

    2016-07-01

    Large superconducting FeSe crystals of (001) orientation have been prepared via a hydrothermal ion release/introduction route for the first time. The hydrothermally derived FeSe crystals are up to 10 mm×5 mm×0.3 mm in dimension. The pure tetragonal FeSe phase has been confirmed by x-ray diffraction (XRD) and the composition determined by both inductively coupled plasma atomic emission spectroscopy (ICP-AES) and energy dispersive x-ray spectroscopy (EDX). The superconducting transition of the FeSe samples has been characterized by magnetic and transport measurements. The zero-temperature upper critical field H c2 is calculated to be 13.2-16.7 T from a two-band model. The normal-state cooperative paramagnetism is found to be predominated by strong spin frustrations below the characteristic temperature T sn, where the Ising spin nematicity has been discerned in the FeSe superconductor crystals as reported elsewhere. Project supported by the National Natural Science Foundation of China (Grant Nos. 11574370, 11274358, and 11190020), the National Basic Research Program of China (Grant No. 2013CB921700), and the Strategic Priority Research Program (B) of the Chinese Academy of Sciences (Grant No. XDB07020100).

  7. Ion acoustic shock waves in a degenerate relativistic plasma with nuclei of heavy elements

    NASA Astrophysics Data System (ADS)

    Atteya, A.; Behery, E. E.; El-Taibany, W. F.

    2017-03-01

    Based on the quantum hydrodynamics theory, a rigorous model for ion acoustic shock waves (IASWs) in a degenerate relativistic plasma with heavy ion nuclei is presented. Two cases are considered: the ultra-relativistic case and the non-relativistic case. A Korteweg-de Vries-Burger's (KdVB) equation describing IASWs in such plasma is derived, then its explicit as well as oscillatory solutions are deduced. It is found that the shape of IASWs is influenced by the particle density of degenerate electrons, the concentration of heavy elements, the viscosity coefficient, and the quantum Bohm potential term. The results should be useful in understanding the shock wave characteristics in degenerate plasma which is found in compact astrophysical objects.

  8. Effect of heavy metal ions on the release of reactive oxygen intermediates by bovine alveolar macrophages.

    PubMed

    Schlüter, T; Berg, I; Dörger, M; Gercken, G

    1995-04-12

    Short-term incubations of bovine alveolar macrophages (BAM) with metal-containing dusts induce the release of reactive oxygen intermediates (ROI). Incubations of BAM (90 min) with dissolved metal compounds (0.1-100 microM) combined with quartz dusts were performed to investigate the effects of single elements on BAM stimulation. As(III), as well as the calcium antagonists, Ni(II) and Ce(III), inhibited the secretion of superoxide anions (O2-) and hydrogen peroxide (H2O2). O2- concentrations were lowered by Mn(II) and Fe(II). Increased ROI concentrations were observed with V(IV) (O2- and H2O2) and Fe(III) (O2-). The addition of Cd(II), Cr(III) and V(V) showed no effect on the dust-induced respiratory burst. The influence of insoluble heavy metal compounds on ROI secretion by BAM were studied with metal oxide-coated silica particles. In most cases the release of ROI was not affected by the chemical modification of the particle surface. Coating with CuO markedly lowered the concentrations of O2- and H2O2, whereas vanadium(IV) oxide considerably increased both ROIs. Although most of the investigated metal compounds did not alter ROI secretion our present results with V(IV) and Fe(III) confirm our recent statistical evaluation of the effects of heavy metal-containing dusts on ROI secretion (Berg et al., 1993, J. Toxicol. Environ. Health 39, 341).

  9. Microbial acidification and pH effects on trace element release from sewage sludge.

    PubMed

    Qureshi, Shabnam; Richards, Brian K; Steenhuis, Tammo S; McBride, Murray B; Baveye, Philippe; Dousset, Sylvie

    2004-11-01

    Leaching of sludge-borne trace elements has been observed in experimental and field studies. The role of microbial processes in the mobilization of trace elements from wastewater sludge is poorly defined. Our objectives were to determine trace element mobilization from sludge subjected to treatments representing microbial acidification, direct chemical acidification and no acidification, and to determine the readsorption potential of mobilized elements using calcareous sand. Triplicate columns (10-cm diameter) for incubation and leaching of sludge had a top layer of digested dewatered sludge (either untreated, acidified with H2SO4, or limed with CaCO3; all mixed with glass beads to prevent ponding) and a lower glass bead support bed. Glass beads in the sludge layer, support layer or both were replaced by calcareous sand in four treatments used for testing the readsorption potential of mobilized elements. Eight sequential 8-day incubation and leaching cycles were operated, each consisting of 7.6 d of incubation at 28 degrees C followed by 8 h of leaching with synthetic acid rain applied at 0.25 cm/h. Leachates were analyzed for trace elements, nitrate and pH, and sludge layer microbial respiration was measured. The largest trace element, nitrate and S losses occurred in treatments with the greatest pH depression and greatest microbial respiration rates. Cumulative leaching losses from both microbial acidification and direct acidification treatments were > 90% of Zn and 64-80% of Cu and Ni. Preventing acidification with sludge layer lime or sand restricted leaching for all trace elements except Mo. Results suggested that the primary microbial role in the rapid leaching of trace elements was acidification, with results from direct acidification being nearly identical to microbial acidification. Microbial activity in the presence of materials that prevented acidification mobilized far lower concentrations of trace elements, with the exception of Mo. Trace elements

  10. Ion release from copper phosphate cement and influence on Streptococcus mutans growth in vitro: a comparative study.

    PubMed

    Foley, Jennifer; Blackwell, Alison

    2003-01-01

    The aim of this study was to compare the effects of a black copper cement (BCC), an established restorative material (a conventional glass ionomer cement) and two temporary restorative materials (a zinc phosphate and a zinc polycarboxylate cement) on the growth of Streptococcus mutans in vitro, and to correlate bacterial growth with ion release from each material. Test specimens were eluted in either 0.1 M lactic acid, pH 4, or 0.1 M sodium chloride, pH 7. At 2 days, 7 days, 28 days and 6 months, eluates were inoculated with S. mutans and bacterial growth was recorded. Metal ion (Cu(2+), Zn(2+ )and Mg(2+)) and fluoride release were measured. At most immersion times, the different materials had a statistically significant inhibitory effect on bacterial growth compared to the respective control, at both pH levels. The inhibitory effect decreased with time and in most cases was associated with high levels of ion release at the beginning of the experimental period, followed by significantly lower levels. For BCC, there were statistically significant relationships between the median rates of growth of S. mutans in the presence of BCC eluates and the median values for release of copper and zinc, although not magnesium. Of the different materials, BCC demonstrated greatest antibacterial activity.

  11. Functionalized Mesoporous Silica via an Aminosilane Surfactant Ion Exchange Reaction: Controlled Scaffold Design and Nitric Oxide Release

    PubMed Central

    2015-01-01

    Nitric oxide-releasing mesoporous silica nanoparticles (MSNs) were prepared using an aminosilane-template surfactant ion exchange reaction. Initially, bare silica particles were synthesized under basic conditions in the presence of cetyltrimethylammonium bromide (CTAB). These particles were functionalized with nitric oxide (NO) donor precursors (i.e., secondary amines) via the addition of aminosilane directly to the particle sol and a commensurate ion exchange reaction between the cationic aminosilanes and CTAB. N-Diazeniumdiolate NO donors were formed at the secondary amines to yield NO-releasing MSNs. Tuning of the ion exchange-based MSN modification approach allowed for the preparation of monodisperse particles ranging from 30 to 1100 nm. Regardless of size, the MSNs stored appreciable levels of NO (0.4–1.5 μmol mg–1) with tunable NO release durations (1–33 h) dependent on the aminosilane modification. Independent control of NO release properties and particle size was achieved, demonstrating the flexibility of this novel MSN synthesis over conventional co-condensation and surface grafting strategies. PMID:26717238

  12. A possible new host mineral of large-ion elements in the Earth's deep interior

    NASA Astrophysics Data System (ADS)

    Kawai, K.; Tsuchiya, T.

    2015-12-01

    The radiogenic heat production as well as the secular cooling is essential in order to better understand the thermal history and dynamics in the Earth. Potassium is thought to be one of the important radioactive elements in the Earth's interior. Although these elements are concentrated in the continental and oceanic crusts due to chemical differentiations through partial melting at plate boundaries due to their large ion-radii, they have been considered to return into the deep mantle accompanied with subducting slab through time . However, since there are few studies on host minerals of potassium in the high P,T condition, it has yet to be clear how much and where host rocks of such radioactive elements exist in the Earth. Hence, it is important to understand the fate of the potassium-bearing phase subducted into the deep Earth's interior. Here we have studied the high-pressure stability and elasticity of KMg2Al5SiO12 hexagonal aluminous phase (K-Hex with three different size of cation cites, by means of the density functional computation method. Results indicate that the K-Hex phase remains mechanically stable up to 150 GPa and also energetically more stable than an isochemical form with the calcium-ferrite (K-CF) and calcium-titanate (K-CT) type structure with two different size of cation cites. In addition, when the spinel composition coexists with the K-hollandite (K-Hol) phase, which is ), which is considered to be able to host potassium the K-Hex phase becomes more stable than the K-Hol phase at pressures above ~27 GPa. These demonstrate that the Hex phase is substantially stable in the lower mantle, suggesting that it could be a potential host of potassium and other incompatible large-ion elements.

  13. Hornblende-melt trace-element partitioning measured by ion microprobe

    USGS Publications Warehouse

    Sisson, T.W.

    1994-01-01

    Trace-element abundances were measured in situ by ion microprobe in five samples of hornblende and melt ranging from basaltic andesite to high-silica rhyolite. Except for one sample, for which quench overgrowth or disequilibrium is suspected, the abundance ratios show systematic inter-element and inter-sample variations, and probably approach true partition coefficients. Apparent partition coefficients are reported for La, Ce, Nd, Sm, Dy, Er, Yb, Sc, Ti, V, Cr, Sr, Y and Zr. Rare-earth elements (REE) and Y form smooth convex-upward partitioning patterns that rise to higher D-values and become increasingly convex in more evolved samples. Apparent partition coefficients for REE, Y, Ti, V and Cr can be parameterized as functions of the distribution of Ca between hornblende and melt, giving expressions to predict hornblende-melt trace-element partitioning values. These expressions are used to show that heavy REE-enriched hornblende/whole-rock REE abundance patterns in granitoids may result from partial re-equilibration of hornblende and late-stage residual liquids rather than from anomalous partitioning values.

  14. Neutron interrogation to identify chemical elements with an ion-tube neutron source (INS)

    SciTech Connect

    Alvarez, R.A.; Dougan, A.D.; Rowland, M.R.; Wang, T.F.

    1994-04-07

    A non-destructive analysis technique using a portable, electric ion-tube neutron source (INS) and gamma ray detector has been used to identify the key constituent elements in a number of sealed munitions, and from the elemental makeup, infer the types of agent within each. The high energy (14 MeV) and pulsed character of the neutron flux from an INS provide a method of measuring, quantitatively, the oxygen, carbon, and fluorine content of materials in closed containers, as well as the other constituents that can be measured with low-energy neutron probes. The broad range of elements that can be quantitatively measured with INS-based instruments provides a capability of verifying common munition fills; it provides the greatest specificity of any portable neutron-based technique for determining the full matrix of chemical elements in completely unrestricted sample scenarios. The specific capability of quantifying the carbon and oxygen content of materials should lead to a fast screening technique which, can discriminate very quickly between high-explosive and chemical agent-filled containers.

  15. Early time evolution of negative ion clouds and electron density depletions produced during electron attachment chemical release experiments

    NASA Technical Reports Server (NTRS)

    Scales, W. A.; Bernhardt, P. A.; Ganguli, G.

    1994-01-01

    Two-dimensional electrostatic particle-in-cell simulations are used to study the early time evolution of electron depletions and negative ion clouds produced during electron attachment chemical releases in the ionosphere. The simulation model considers the evolution in the plane perpendicular to the magnetic field and a three-species plasma that contains electrons, positive ions, and also heavy negative ions that result as a by-product of the electron attachment reaction. The early time evolution (less than the negative ion cyclotron period) of the system shows that a negative charge surplus initially develops outside of the depletion boundary as the heavy negative ions move across the boundary. The electrons are initially restricted from moving into the depletion due to the magnetic field. An inhomogenous electric field develops across the boundary layer due to this charge separation. A highly sheared electron flow velocity develops in the depletion boundary due to E x B and Delta-N x B drifts that result from electron density gradients and this inhomogenous electric field. Structure eventually develops in the depletion boundary layer due to low-frequency electrostatic waves that have growth times shorter than the negative ion cyclotron period. It is proposed that these waves are most likely produced by the electron-ion hybrid instability that results from sufficiently large shears in the electron flow velocity.

  16. Influence of multi-element ion beam bombardment on the corrosion behavior of iron and steel

    SciTech Connect

    Wei, Tian; Run, Wu; Weiping, Cai; Rutao, Wang ); Godechot, X.; Brown, I. )

    1991-06-01

    The effect of multi-element ion implantation on the corrosion resistance to acid solution has been studied for stainless steel, medium carbon steel, pure iron, and chromium-deposited iron. The implanted elements were Cu, Mo, Cr, Ni, Yb and Ti at doses of each species of from 5 {times} 10{sup 15} to 1 {times} 10{sup 17} cm{sup {minus}2} and at ion energies of up to 100 keV. The stainless steel used was 18-8 Cr-Ni, and the medium carbon steel was 0.45% C. The implanted samples were soaked in dilute sulfuric acid solution for periods up to 48 hours and the weight loss measured by atomic absorption spectroscopy. The kinetic parameter values describing the weight loss as a function of time were determined for all samples. In this paper we summarize the corrosion resistance behavior for the various different combinations of implanted species, doses, and substrates. The influence of the composition and structure of the modified surface layer is discussed.8 refs., 5 figs., 2 tabs.

  17. The Potential Impacts on Aquatic Ecosystems from the Release of Trace Elements in Geothermal Fluids

    SciTech Connect

    Cushman, R.M.

    2000-03-14

    Geothermal energy will likely constitute an increasing percentage of our nation's future energy ''mix,'' both for electrical and nonelectrical uses. Associated with the exploitation of geothermal resources is the handling and disposal of fluids which contain a wide variety of potentially toxic trace elements. We present analyses of 14 trace elements found in hydrothermal fluids from various geothermal reservoirs in the western United States. The concentrations of these elements vary over orders of magnitude between reservoirs. Potential impacts are conservatively assessed on the basis of (1) toxicity to freshwater biota, and (2) bioaccumulation in food fish to the point where consumption might be hazardous to human health. Trace element concentrations generally range from benign levels to levels which might prove toxic to freshwater biota and contaminate food fisheries. We stress the need for site-specific analyses and careful handling of geothermal fluids in order to minimize potential impacts.

  18. Titanium Ions Release from an Innovative Titanium-Magnesium Composite: an in Vitro Study

    PubMed Central

    Halambek, Jasna; Maldini, Krešimir; Balog, Martin; Križik, Peter; Schauperl, Zdravko; Ćatić, Amir

    2016-01-01

    Background The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. Material and methods Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. Results The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. Conclusion In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested. PMID:27688425

  19. Stabilizing effects of coenzyme Q10 on potassium ion release, membrane potential and fluidity of rabbit red blood cells.

    PubMed

    Shinozawa, S; Araki, Y; Oda, T

    1980-09-01

    The effects of coenzyme Q10 (Co Q10) on potassium ion release, membrane potential and fluidity of rabbit red blood cells were studied. Co Q10 inhibited the increased potassium ion release induced by cetylamine or lysolecithin from the cells. Co Q10 slightly decreased the membrane potential monitored by changes in fluorescence intensity of cyanine dye, 3,3'-dipropyl-2,2'-thiodicarbocyanine iodide [diS-C3-(5)], and also slightly decreased the membrane fluidity measured by using 1,6-diphenyl-1,3,5-hexatriene (DPH). These effects of Co Q10 on the membrane are considered to be due to its membrane stabilizing activity by interaction with lipid bilayers of the membrane.

  20. Corrosion and ion release behavior of Cu/Ti film prepared via physical vapor deposition in vitro as potential biomaterials for cardiovascular devices

    NASA Astrophysics Data System (ADS)

    Liu, Hengquan; Zhang, Deyuan; Shen, Feng; Zhang, Gui; Song, Shenhua

    2012-07-01

    Cu/Ti films of various Cu/Ti ratios were prepared on a TiNi alloy via vacuum arc plasma deposition. The phase composition, structure, and concentration of elements were investigated via X-ray diffraction and X-photoelectron energy spectrum. The hemolysis ratio and platelet adhesion of the different films were characterized to evaluate blood compatibility. The corrosion and ion release behavior were investigated via a typical immersion test and electrochemical method. The growth of endothelial cells (ECs) was investigated, and methylthiazolyte-trazolium method was employed to evaluate the effect of Cu2+. The sophisticated films showed good compatibility. However, with increasing quality ratio of Cu/Ti, the hemolysis ratio increased, and some platelets started to break slightly. The Cu2+ release was gradually stabilized. The open circuit potential of the Cu/Ti film-modified samples was lower than that of the TiNi substrate. The polarization test result indicates that the passivation stability performance of Cu/Ti film samples is less than the TiNi substrate, and is favorable to Cu2+ release. The adhesion and proliferation of ECs would be inhibited with 10 wt.% Cu concentration of the film, and ECs would undergo apoptosis at >50 wt.% concentration. A Cu/Ti film with good compatibility and anti-endothelialization has potential applications for special cardiovascular devices.

  1. Solar Ion Processing of Major Element Surface Compositions of Mature Mare Soils: Insights from Combined XPS and Analytical TEM Observations

    NASA Technical Reports Server (NTRS)

    Christoffersen, R.; Dukes, C.; Keller, L. P.; Baragiola, R.

    2012-01-01

    Solar wind ions are capable of altering the sur-face chemistry of the lunar regolith by a number of mechanisms including preferential sputtering, radiation-enhanced diffusion and sputter erosion of space weathered surfaces containing pre-existing compositional profiles. We have previously reported in-situ ion irradiation experiments supported by X-ray photoelectron spectroscopy (XPS) and analytical TEM that show how solar ions potentially drive Fe and Ti reduction at the monolayer scale as well as the 10-100 nm depth scale in lunar soils [1]. Here we report experimental data on the effect of ion irradiation on the major element surface composition in a mature mare soil.

  2. Light-Controlled Release and Uptake of Zinc Ions in Solution by a Photochromic Terthiazole-Based Ligand.

    PubMed

    Guérin, Juliette; Léaustic, Anne; Berthet, Jérôme; Métivier, Rémi; Guillot, Régis; Delbaere, Stéphanie; Nakatani, Keitaro; Yu, Pei

    2017-03-22

    We have synthesized and fully characterized a photochromic zinc complex with a terphenylthiazole-based ligand with a salen-like cavity. The solution stability of the complex was found to be greatly dependent on the state of the photochromic ligand and an interesting photo-triggered release and uptake of zinc ions was found as well as monitored by its fluorescence. The contrasting stability difference of the zinc complex between its two isomeric states was rationalized by DFT calculations.

  3. Effect of different cleansers on the weight and ion release of removable partial denture: an in vitro study

    PubMed Central

    FELIPUCCI, Daniela N.B.; DAVI, Letícia R.; PARANHOS, Helena F.O.; BEZZON, Osvaldo L.; SILVA, Rodrigo F.; BARBOSA JUNIOR, Fernando; PAGNANO, Valéria O.

    2011-01-01

    Objective Removable partial dentures (RPD) require different hygiene care, and association of brushing and chemical cleansing is the most recommended to control biofilm formation. However, the effect of cleansers has not been evaluated in RPD metallic components. The aim of this study was to evaluate in vitro the effect of different denture cleansers on the weight and ion release of RPD. Material and Methods Five specimens (12x3 mm metallic disc positioned in a 38x18x4 mm mould filled with resin), 7 cleanser agents [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05% sodium hypochlorite (NaOCl), and distilled water (DW) (control)] and 2 cobalt-chromium alloys [DeguDent (DD), and VeraPDI (VPDI)] were used for each experimental situation. One hundred and eighty immersions were performed and the weight was analyzed with a high precision analytic balance. Data were recorded before and after the immersions. The ion release was analyzed using mass spectrometry with inductively coupled plasma. Data were analyzed by two-way ANOVA and Tukey HSD post hoc test at 5% significance level. Results Statistical analysis showed that CT and MI had higher values of weight loss with higher change in VPDI alloy compared to DD. The solutions that caused more ion release were NaOCl and MI. Conclusions It may be concluded that 0.05% NaOCl and Medical Interporous tablets are not suitable as auxiliary chemical solutions for RPD care. PMID:21986653

  4. Application of alpha spectrometry to the discovery of new elements by heavy-ion-beam bombardment

    SciTech Connect

    Nitschke, J.M.

    1983-05-01

    Starting with polonium in 1898, ..cap alpha..-spectrometry has played a decisive role in the discovery of new, heavy elements. For even-even nuclei, ..cap alpha..-spectra have proved simple to interpret and exhibit systematic trends that allow extrapolation to unknown isotopes. The early discovery of the natural ..cap alpha..-decay series led to the very powerful method of genetically linking the decay of new elements to the well-established ..cap alpha..-emission of daughter and granddaughter nuclei. This technique has been used for all recent discoveries of new elements including Z = 109. Up to mendelevium (Z = 101), thin samples suitable for ..cap alpha..-spectrometry were prepared by chemical methods. With the advent of heavy-ion accelerators new sample preparation methods emerged. These were based on the large momentum transfer associated with heavy-ion reactions, which produced energetic target recoils that, when ejected from the target, could be thermalized in He gas. Subsequent electrical deposition or a He-jet technique yielded samples that were not only thin enough for ..cap alpha..-spectroscopy, but also for ..cap alpha..- and ..beta..-recoil experiments. Many variations of these methods have been developed and are discussed. For the synthesis of element 106 an aerosol-based recoil transport technique was devised. In the most recent experiments, ..cap alpha..-spectrometry has been coupled with the magnetic analysis of the recoils. The time from production to analysis of an isotope has thereby been reduced to 10/sup -6/ s; while it was 10/sup -1/ to 10/sup 0/ s for He-jets and 10/sup 1/ to 10/sup 3/ s for rapid chemical separations. Experiments are now in progress to synthesize super heavy elements (SHE) and to analyze them with these latest techniques. Again, ..cap alpha..-spectrometry will play a major role since the expected signature for the decay of a SHE is a sequence of ..cap alpha..-decays followed by spontaneous fission.

  5. Pyroxene-high silica rhyolite trace element partition coefficients measured by ion microprobe

    NASA Astrophysics Data System (ADS)

    Sisson, T. W.

    1991-06-01

    Pyroxene-liquid trace element partition coefficients have been measured in situ by ion microprobe in high silica rhyolites. Partition coefficients are reported for La, Ce, Nd, Sm, Dy, Er, Yb, Sc, Ti, V, Cr, Sr, Y, and Zr. The in situ analyses avoid the problem of contamination of the pyroxene phase by trace element-rich accessory mineral inclusions encountered in traditional bulk phenocryst-glass partitioning studies. Pyroxenes and glasses which have been analyzed are typical of high silica rhyolites worldwide. The samples analyzed are Bishop Tuff, California (augite, hypersthene); Sierra La Primavera, Mexico (ferrohedenbergite); and two samples of the Huckleberry Ridge Tuff, Wyoming (ferroaugite). Rare earth element (REE) partition coefficient patterns are convex-upward and resemble patterns determined in less silicic bulk compositions. Partition coefficients for the REEs Sr, Zr, and Cr show correlations with the Mg# of clinopyroxene, suggesting that crystal composition influences the fine structure of partitioning patterns. The overall similarity of partitioning patterns between samples indicates that the partition coefficients determined in this study can be generally applied in the geochemical modeling of high silica rhyolites.

  6. Low-Resistance Dual-Purpose Air Filter Releasing Negative Ions and Effectively Capturing PM2.5.

    PubMed

    Zhao, Xinglei; Li, Yuyao; Hua, Ting; Jiang, Pan; Yin, Xia; Yu, Jianyong; Ding, Bin

    2017-04-05

    The fatal danger of pollution due to particulate matter (PM) calls for both high-efficiency and low-resistance air purification materials, which also provide healthcare. This is however still a challenge. Herein, a low-resistance air filter capable of releasing negative ions (NIs) and efficiently capturing PM2.5 was prepared by electrospinning polyvinylidene fluoride (PVDF) fibers doped with negative ions powder (NIPs). The air-resistance of fibrous membranes decreased from 9.5 to 6 Pa (decrease of 36%) on decreasing the average fiber diameter from 1.16 to 0.41 μm. Moreover, the lower rising rate of air-resistance with reduction in pore size, for fibrous membranes with thinner fiber diameter was verified. In addition, a single PVDF/NIPs fiber was provided with strong surface potentials, due to high fluorine electronegativity, and tested using atomic force microscopy. This strong surface potential resulted in higher releasing amounts of NIs (RANIs). Interestingly, reduction of fiber diameter favored the alleviation of the shielding effects on electric field around fibers and promoted the RANIs from 798 to 1711 ions cc(-1). Moreover, by regulating the doping contents of NIPs, the RANIs increased from 1711 to 2818 ions cc(-1). The resultant fibrous membranes showed low air resistance of 40.5 Pa. Field-tests conducted in Shanghai showed stable PM2.5 purification efficiency of 99.99% at high RANIs, in the event of haze.

  7. Release of nickel and chromium ions in the saliva of patients with fixed orthodontic appliance: An in-vivo study

    PubMed Central

    Dwivedi, Anoop; Tikku, Tripti; Khanna, Rohit; Maurya, Rana Pratap; Verma, Geeta; Murthy, R. C.

    2015-01-01

    Introduction: Various components of fixed orthodontic appliances are continuously interacting with saliva and other fluids in the mouth releasing various metal ions including nickel and chromium that can cause damaging effects if their concentration exceeds above the toxic dose. Aim: To determine and compare the level of nickel and chromium in the saliva of patients undergoing fixed orthodontic treatment at different time periods. Materials and Methods: The sample of saliva of 13 patients was taken at different time periods that is: Group 1 (before appliance placement), Group II, III, and IV (after 1-week, 1-month, and 3 months of appliance placement respectively). The fixed appliance comprised of brackets, bands, buccal tubes, lingual sheath, transpalatal arch and wires composed of Ni-Ti and stainless steel. The level of ions was determined using graphite furnace atomic absorption spectro-photometry. The data thus obtained were statistically analyzed using SPSS Statistical Analysis Software (Version 15.0). Results: Level of nickel and chromium in saliva was highest in Group II and lowest in Groups I for both the ions. On comparison among different Groups, it was statistically significant for all the groups (<0.001) except between Group III and Group IV. Conclusion: The release of nickel and chromium was maximum at 1-week and then the level gradually declined. These values were well below the toxic dose of these ions. The results should be viewed with caution in subjects with Ni hypersensitivity. PMID:26668455

  8. [Cholesterol and lipid rafts in the biological membranes. Role in the release, reception and ion channel functions].

    PubMed

    Petrov, A M; Zefirov, A L

    2013-01-01

    Traditionally, membrane protein molecules that form ion channels, transporters, pumps, signaling complexes, machine of exo- and endocytosis is assigned as the main players of the cellular processes. Recently, the findings that indicate the importance of lipids in regulating of cell physiology are accumulated. Attention is attracting to cholesterol molecule because it can directly interact with different proteins and together with sphingolipids to form membrane microdomains (lipid rafts). Many receptors (for neurotransmitters, hormones, growth factors), signaling proteins and proteins involved in vesicular and ion transport are concentrated in the lipid rafts. Changes in stability and structure of rafts cause dramatic cellular dysfunction. In the review the current views on lipid variants that make up the biological membrane, the distribution of cholesterol, the organization and the formation of lipid rafts and caveolae are described. Accent is made on researches that focus on the significance of lipid rafts in the extra- and intracellular signaling, neurotransmitters release, receptor and ion channels function at the excitable cells.

  9. Measurement of kinetic energy release in CO fragmentation by charge-changing collisions of fast heavy ions

    SciTech Connect

    Mizuno, T.; Yamada, T.; Tsuchida, H.; Itoh, A.; Nakai, Y.

    2010-01-15

    We study ionization and fragmentation of CO in electron loss and capture collisions of B{sup 2+}, O{sup 2+}, and Si{sup 2+} ions at an energy of 71.4 keV/u (v=1.69 a.u.). Coincidence measurements of fragment ions from CO and charge-selected ions were performed by means of a momentum three-dimensional imaging technique. Production cross sections of CO{sup r+} and branching ratios into various fragmentation channels were obtained for r=1-4. We also measured kinetic energy release (KER) in individual fragmentation channels. The KER spectra for r<=2 are found to be different for electron loss and capture collisions, while the difference becomes small for r>=3. As a measure of the degree of molecular fragmentation, the magnitude of the binding energy of the relevant electronic states seems the important parameter both in loss and capture collisions.

  10. The Double Solid Reactant Method for modeling the release of trace elements from dissolving solid phases: I. Outline and limitations

    NASA Astrophysics Data System (ADS)

    Accornero, Marina; Marini, Luigi

    2008-10-01

    A Double Solid Reactant Method was elaborated from a suggestion of Marini (Geological sequestration of carbon dioxide: Thermodynamics, kinetics, and reaction path modeling. Developments in Geochemistry, Elsevier, Amsterdam, 2007) to simulate the release of trace elements during the progressive dissolution of solid phases. The method is based on the definition, for each dissolving solid, of both an entity whose thermodynamic and kinetic properties are known (either a pure mineral or a solid mixture) and a special reactant, that is, a material of known stoichiometry and unknown thermodynamic and kinetic properties. The special reactant is utilised to take into account the concentrations of trace elements in the dissolving solid phase. In this communication, the influence of several trace elements on the Δ G f o, Δ G r o and log K of the minerals considered by Lelli et al. (Environ Geol, 2007) and Accornero and Marini (Geobasi, 2007a; Proceedings of IMWA symposium, Cagliari, 27 31 May 2007b) was evaluated assuming ideal mixing in the solid state. These effects were found to be negligible for albite and the leucite latitic glass, limited for muscovites and chlorites, and slightly more important for apatites. These influences become progressively higher with increasing concentration of trace elements in these minerals. Based on these deviations in thermodynamic parameters, special reactants should not include oxide components with molar fractions higher than 0.003.

  11. Iron sulfide attenuates the methanogenic toxicity of elemental copper and zinc oxide nanoparticles and their soluble metal ion analogs.

    PubMed

    Gonzalez-Estrella, Jorge; Gallagher, Sara; Sierra-Alvarez, Reyes; Field, Jim A

    2016-04-01

    Elemental copper (Cu(0)) and zinc oxide (ZnO) nanoparticle (NP) toxicity to methanogens has been attributed to the release of soluble metal ions. Iron sulfide (FeS) partially controls the soluble concentration of heavy metals and their toxicity in aquatic environments. Heavy metals displace the Fe from FeS forming poorly soluble metal sulfides in the FeS matrix. Therefore, FeS may be expected to attenuate the NP toxicity. This work assessed FeS as an attenuator of the methanogenic toxicity of Cu(0) and ZnO NPs and their soluble salt analogs. The toxicity attenuation capacity of fine (25-75μm) and coarse (500 to 1200μm) preparations of FeS (FeS-f and FeS-c respectively) was tested in the presence of highly inhibitory concentrations of CuCl2, ZnCl2 Cu(0) and ZnO NPs. FeS-f attenuated methanogenic toxicity better than FeS-c. The results revealed that 2.5× less FeS-f than FeS-c was required to recover the methanogenic activity to 50% (activity normalized to uninhibited controls). The results also indicated that a molar FeS-f/Cu(0) NP, FeS-f/ZnO NP, FeS-f/ZnCl2, and FeS-f/CuCl2 ratio of 2.14, 2.14, 4.28, and 8.56 respectively, was necessary to recover the methanogenic activity to >75%. Displacement experiments demonstrated that CuCl2 and ZnCl2 partially displaced Fe from FeS. As a whole, the results indicate that not all the sulfide in FeS was readily available to react with the soluble Cu and Zn ions which may explain the need for a large stoichiometric excess of FeS to highly attenuate Cu and Zn toxicity. Overall, this study provides evidence that FeS attenuates the toxicity caused by Cu(0) and ZnO NPs and their soluble ion analogs to methanogens.

  12. Iron Sulfide Attenuates the Methanogenic Toxicity of Elemental Copper and Zinc Oxide Nanoparticles and their Soluble Metal Ion Analogs

    PubMed Central

    Gonzalez-Estrella, Jorge; Gallagher, Sara; Sierra-Alvarez, Reyes; Field, Jim A.

    2016-01-01

    Elemental copper (Cu0) and zinc oxide (ZnO) nanoparticle (NP) toxicity to methanogens has been attributed to the release of soluble metal ions. Iron sulfide (FeS) partially controls the soluble concentration of heavy metals and their toxicity in aquatic environments. Heavy metals displace the Fe from FeS forming poorly soluble metal sulfides in the FeS matrix. Therefore, FeS may be expected to attenuate the NP toxicity. This work assessed FeS as an attenuator of the methanogenic toxicity of Cu0 and ZnO NPs and their soluble salt analogs. The toxicity attenuation capacity of fine (25–75 µm) and coarse (500 to 1200 µm) preparations of FeS (FeS-f and FeS-c respectively) was tested in the presence of highly inhibitory concentrations of CuCl2, ZnCl2 Cu0 and ZnO NPs. FeS-f attenuated methanogenic toxicity better than FeS-c. The results revealed that 2.5× less FeS-f than FeS-c was required to recover the methanogenic activity to 50% (activity normalized to uninhibited controls). The results also indicated that a molar FeS-f/Cu0 NP, FeS-f/ZnO NP, FeS-f/ZnCl2, and FeS-f/CuCl2 ratio of 2.14, 2.14, 4.28, and 8.56 respectively, was necessary to recover the methanogenic activity to >75%. Displacement experiments demonstrated that CuCl2 and ZnCl2 partially displaced Fe from FeS. As a whole, the results indicate that not all the sulfide in FeS was readily available to react with the soluble Cu and Zn ions which may explain the need for a large stoichiometric excesses of FeS to highly attenuate Cu and Zn toxicity. Overall, this study provides evidence that FeS attenuates the toxicity caused by Cu0 and ZnO NPs and their soluble ion analogs to methanogens. PMID:26803736

  13. Mathematical modeling and remote monitoring of ion-exchange separation of transplutonium elements

    SciTech Connect

    Tselishchev, I.V.; Elesin, A.A.

    1988-07-01

    A mathematical model and calculational algorithms for the elution curves for ion-exchange separation of transplutonium elements (TPE) and the limits of optimal fractionation of the substances being separated, based on indicators of the process (yield, purification), are presented. The calculational programs are part of the programming provision of a small informational-calculational system based on the microcomputer Elektronika DZ-28, intended for remote monitoring of TPE separation. The elaborated programs can be implemented in the preliminary choice of necessary conditions of the TPE separation process, and also during and after the separation process for comparison of calculated results with the results of continuous, on-line remote monitoring and with the results of laboratory sample analysis. The possible application of the programs has been checked in the instance of the separation of curium and americium, and einsteinium and californium, the results of which are in satisfactory agreement with the results of remote and laboratory-analytical monitoring.

  14. Ion microprobe elemental analyses of impact features on interplanetary dust experiment sensor surfaces

    NASA Technical Reports Server (NTRS)

    Simon, Charles G.; Hunter, Jerry L.; Wortman, Jim J.; Griffis, Dieter P.

    1992-01-01

    Hypervelocity impact features from very small particles (less than 3 microns in diameter) on several of the electro-active dust sensors used in the Interplanetary Dust Experiment (IDE) were subjected to elemental analysis using an ion microscope. The same analytical techniques were applied to impact and containment features on a set of ultra-pure, highly polished single crystal germanium wafer witness plates that were mounted on tray B12. Very little unambiguously identifiable impactor debris was found in the central craters or shatter zones of small impacts in this crystalline surface. The surface contamination, ubiquitous on the surface of the Long Duration Exposure Facility, has greatly complicated data collection and interpretation from microparticle impacts on all surfaces.

  15. Trace element release from estuarine sediments of South Mosquito Lagoon near Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Menon, M. P.; Ghuman, G. S.; Emeh, C. O.

    1979-01-01

    Analytical partitioning of four trace metals in estuarine sediments collected from eight sites in South Mosquito Lagoon near Kennedy Space Center, in terms of four different categories was accomplished using four different extraction techniques. The concentrations of the four trace metals, Zn, Mn, Cd, and Cu, released in interstitial water extract, 1 N ammonium acetate extract, conc. HCl extract and fusion extract of sediments as well as their concentrations in water samples collected from the same location were determined using flame atomic absorption technique. From the analytical results the percentages of total amount of each metal distributed among four different categories, interstitial water phase, acetate extractable, acid extractable and detrital crystalline material, were determined. Our results suggest that analytical partitioning of trace metals in estuarine sediments may be used to study the mechanism of incorporation of trace metals with sediments from natural waters. A correlation between the seasonal variation in the concentration of acetate extractable trace metals in the sediment and similar variation in their concentration in water was observed. A mechanism for the release of trace metals from estuarine sediments to natural water is also suggested.

  16. Oral sustained-release suspension based on a novel taste-masked and mucoadhesive carrier-ion-exchange fiber.

    PubMed

    Yuan, Jing; Liu, Tiaotiao; Li, Heran; Shi, Tianyu; Xu, Jie; Liu, Hongzhuo; Wang, Zhiguo; Wang, Qifang; Xu, Lu; Wang, Yan; Li, Sanming

    2014-09-10

    The purpose of this study was to evaluate the feasibility of ion-exchange fiber ZB-1 as a novel carrier in oral taste-masked mucoadhesive sustained-release suspensions. Propranolol (PPN) hydrochloride was selected as a model drug with good water solubility, short half life and bitter taste. The PPN-fiber complexes (PF) were prepared by a batch process and coated with Eudragit(®) RS100. Gamma scintigraphy was performed on fasted volunteers revealed about 30% ZB-1 and more than 50% coated ZB-1 were still remaining in the stomach at 6h. In vitro results showed the releases of PF and coated PPN-fiber complexes (C-PF) were sustained. The release, drug content and particle size of C-PF were influenced by coat to core ratio, concentration of coating material and rotation rate. The suspension was stable after standing for 30 days in 0.5% Carbopol(®) with no release rate and taste changed. The administration of C-PF suspension to rats resulted a significant different (P<0.05) improvement of the plasma drug level and prolongation of the release. However, because of the burst effect, the Cmax values of PF suspension didn't differ from drug solution (P>0.05). Furthermore, a linear relationship between in vitro dissolution and in vivo absorption was observed.

  17. Cellulose acetate butyrate microcapsules containing dextran ion-exchange resins as self-propelled drug release system.

    PubMed

    Fundueanu, Gheorghe; Constantin, Marieta; Esposito, Elisabetta; Cortesi, Rita; Nastruzzi, Claudio; Menegatti, Enea

    2005-07-01

    Sulfopropylated dextran microspheres (SP-Ms), (Dm = 80 microm) loaded with a water soluble drug (Tetracycline HCl), were included in cellulose acetate butyrate (CAB) microcapsules. Spherical CAB microcapsules were obtained by oil in water (o/w) solvent evaporation method in the presence of an inert solvent as cyclohexane (CyH) or n-hexane (N-Hex), and different excipients (Phospholipon, Tween, Span, Eudragit RS 100). Chloroform was found to be the best solvent for the preparation of the microcapsules. Also, the sphericity as well as the porosity of the microcapsules was controlled by the presence of an inert solvent. The final concentration of the drug in CAB microparticles was up to 25% (w/w). The key factors for the successful preparation were also the viscosity of the polymer, while the wettability of the resulted microcapsules, the temperature of the preparation, and the porosity have modulated the release of the drug. The higher is the amount of encapsulated microspheres the thinner is the CAB wall between the compartments created by their incorporation. When these microspheres come in contact with the release medium, the pressure created by their swelling breaks the polymer film and the drug starts to be released. The more drug is released in phosphate buffer the higher is the swelling degree of the encapsulated ion exchange resins and the force created by their supplementary swelling will break the more resistants walls. In this way a self-propelled drug release is achieved, until almost all drug was eliberated.

  18. Normal pituitary hormone response to thyrotrophin and gonadotrophin releasing hormones in subjects exposed to elemental mercury vapour.

    PubMed Central

    Erfurth, E M; Schütz, A; Nilsson, A; Barregård, L; Skerfving, S

    1990-01-01

    Exposure to elemental mercury (Hg) vapour results in an accumulation of Hg in the pituitary, the thyroid, and the testis. In this study, basal serum concentrations of pituitary hormones (thyrotrophin (TSH), prolactin (PRL), follicle stimulating hormone (FSH), and luteinising hormone (LH] or their response after administration of thyrotrophin and gonadotrophin releasing hormones did not differ between 11 male workers (mean urinary Hg (U Hg) concentration 26 nmol/mmol creatinine) and nine male dentists (U Hg concentration 1.3 nmol/mmol creatinine) exposed to elemental Hg vapour when compared with matched referent groups (U Hg concentration 0.6 and 0.4 nmol/mmol creatinine). Thus there was no evidence of an effect of Hg on the pituitary. Neither was there any association between exposure to Hg and serum concentrations of free thyroid hormones (S FT3, S FT4), testosterone, or cortisol. Increased plasma concentrations of selenium (Se) were associated with increased basal serum concentrations of TSH, decreased concentrations of basal serum cortisol, and decreased release of FSH. PMID:2119795

  19. Multiple roles of calcium ions in the regulation of neurotransmitter release.

    PubMed

    Neher, Erwin; Sakaba, Takeshi

    2008-09-25

    The intracellular calcium concentration ([Ca(2+)]) has important roles in the triggering of neurotransmitter release and the regulation of short-term plasticity (STP). Transmitter release is initiated by quite high concentrations within microdomains, while short-term facilitation is strongly influenced by the global buildup of "residual calcium." A global rise in [Ca(2+)] also accelerates the recruitment of release-ready vesicles, thereby controlling the degree of short-term depression (STD) during sustained activity, as well as the recovery of the vesicle pool in periods of rest. We survey data that lead us to propose two distinct roles of [Ca(2+)] in vesicle recruitment: one accelerating "molecular priming" (vesicle docking and the buildup of a release machinery), the other promoting the tight coupling between releasable vesicles and Ca(2+) channels. Such coupling is essential for rendering vesicles sensitive to short [Ca(2+)] transients, generated during action potentials.

  20. Template copolymerization to control site structure around metal ions: Applications towards sensing and gas storage and release

    NASA Astrophysics Data System (ADS)

    Mitchell-Koch, Jeremy T.

    The development of functional materials for sensing and gas storage and release is useful in a number of chemical and biological applications. Investigating function of molecularly imprinted polymers (MIP), often used for these purposes, has relied on circumstantial evidence because direct examination of immobilized sites is not possible. Described in this dissertation is the design, synthesis, characterization and function studies of materials synthesized by template copolymerization methods. Metal ions exhibit unique spectroscopic properties and their utilization makes site examination more feasible. Ligand binding modulates these properties such that the event can be measured by spectroscopy. The metal ion's secondary coordination environment can also be tuned to increase or decrease function of the material. In Chapter Two the utilization of template copolymerization to immobilize a europium-containing compound for the detection of volatile organic compounds is described. Luminescence of the immobilized complex is quenched in the presence of volatile organic compounds (VOC). The quenching effect is dependent on concentration of VOC and the nature of polymeric host. Chapters Three and Four describe the development of materials for the photolytic release of nitric oxide (NO). In Chapter Three, a novel manipulation of the immobilized complex is employed to produce binding sites that contain ligands covalently embedded into the host in a position to bind the metal ion upon NO release in order to block rebinding. Incompatible binding affinities of the iron-containing templates made it impossible to study NO photo-release from this material. Second-row transition metals are more compatible with NO binding, and Chapter Four describes a ruthenium salen-containing polymer that releases NO in response to light. Additionally, transfer of NO to a metalloporphyrin and myoglobin has been achieved. This is the first report of photolytic heterogeneous NO transfer by a material

  1. Determination of trace element mineral/liquid partition coefficients in melilite and diopside by ion and electron microprobe techniques

    NASA Technical Reports Server (NTRS)

    Kuehner, S. M.; Laughlin, J. R.; Grossman, L.; Johnson, M. L.; Burnett, D. S.

    1989-01-01

    The applicability of ion microprobe (IMP) for quantitative analysis of minor elements (Sr, Y, Zr, La, Sm, and Yb) in the major phases present in natural Ca-, Al-rich inclusions (CAIs) was investigated by comparing IMP results with those of an electron microprobe (EMP). Results on three trace-element-doped glasses indicated that it is not possible to obtain precise quantitative analysis by using IMP if there are large differences in SiO2 content between the standards used to derive the ion yields and the unknowns.

  2. Trace elements and common ions in southeastern Idaho snow: Regional air pollutant tracers for source area emissions

    USGS Publications Warehouse

    Abbott, M.; Einerson, J.; Schuster, P.; Susong, D.; Taylor, H.E.; ,

    2004-01-01

    Snow sampling and analysis methods which produce accurate and ultra-low measurements of trace elements and common ion concentration in southeastern Idaho snow, were developed. Snow samples were collected over two winters to assess trace elements and common ion concentrations in air pollutant fallout across the southeastern Idaho. The area apportionment of apportionment of fallout concentrations measured at downwind location were investigated using pattern recognition and multivariate statistical technical techniques. Results show a high level of contribution from phosphates processing facilities located outside Pocatello in the southern portion of the Eastern Snake River Plain, and no obvious source area profiles other than at Pocatello.

  3. Manufacturing and characterization of a ceramic microcombustor with integrated oxygen storage and release element

    NASA Astrophysics Data System (ADS)

    Khaji, Z.; Sturesson, P.; Klintberg, L.; Hjort, K.; Thornell, G.

    2015-10-01

    A microscale ceramic high-temperature combustor with a built-in temperature sensor and source of oxygen has been designed, manufactured and characterized. The successful in situ electroplating and oxidation of copper, and the use of copper oxide as the source of oxygen were demonstrated. It was shown that residual stresses from electroplating, copper oxidation and oxide decomposition did not cause much deformation of the substrate but influenced mainly the integrity and adhesion of the metal films. The process had influence on the electrical resistances, however. Calibration of the temperature sensor and correlation with IR thermography up to 1000 °C revealed a nearly linear sensor behavior. Demonstration of combustion in a vacuum chamber proved that no combustion had occurred before release of oxygen from the metal oxide resource.

  4. Intracellular Calcium Mobilization in Response to Ion Channel Regulators via a Calcium-Induced Calcium Release Mechanism

    PubMed Central

    Petrou, Terry; Olsen, Hervør L.; Thrasivoulou, Christopher; Masters, John R.; Ashmore, Jonathan F.

    2017-01-01

    Free intracellular calcium ([Ca2+]i), in addition to being an important second messenger, is a key regulator of many cellular processes including cell membrane potential, proliferation, and apoptosis. In many cases, the mobilization of [Ca2+]i is controlled by intracellular store activation and calcium influx. We have investigated the effect of several ion channel modulators, which have been used to treat a range of human diseases, on [Ca2+]i release, by ratiometric calcium imaging. We show that six such modulators [amiodarone (Ami), dofetilide, furosemide (Fur), minoxidil (Min), loxapine (Lox), and Nicorandil] initiate release of [Ca2+]i in prostate and breast cancer cell lines, PC3 and MCF7, respectively. Whole-cell currents in PC3 cells were inhibited by the compounds tested in patch-clamp experiments in a concentration-dependent manner. In all cases [Ca2+]i was increased by modulator concentrations comparable to those used clinically. The increase in [Ca2+]i in response to Ami, Fur, Lox, and Min was reduced significantly (P < 0.01) when the external calcium was reduced to nM concentration by chelation with EGTA. The data suggest that many ion channel regulators mobilize [Ca2+]i. We suggest a mechanism whereby calcium-induced calcium release is implicated; such a mechanism may be important for understanding the action of these compounds. PMID:27980039

  5. Ni ion release, osteoblast-material interactions, and hemocompatibility of hafnium-implanted NiTi alloy.

    PubMed

    Zhao, Tingting; Li, Yan; Zhao, Xinqing; Chen, Hong; Zhang, Tao

    2012-04-01

    Hafnium ion implantation was applied to NiTi alloy to suppress Ni ion release and enhance osteoblast-material interactions and hemocompatibility. The auger electron spectroscopy, x-ray photoelectron spectroscopy, and atomic force microscope results showed that a composite TiO(2)/HfO(2) nanofilm with increased surface roughness was formed on the surface of NiTi, and Ni concentration was reduced in the superficial surface layer. Potentiodynamic polarization tests displayed that 4 mA NiTi sample possessed the highest E(br) - E(corr), 470 mV higher than that of untreated NiTi, suggesting a significant improvement on pitting corrosion resistance. Inductively coupled plasma mass spectrometry tests during 60 days immersion demonstrated that Ni ion release rate was remarkably decreased, for example, a reduction of 67% in the first day. The water contact angle increased and surface energy decreased after Hf implantation. Cell culture and methyl-thiazol-tetrazolium indicated that Hf-implanted NiTi expressed enhanced osteoblasts adhesion and proliferation, especially after 7 days culture. Hf implantation decreased fibrinogen adsorption, but had almost no effect on albumin adsorption. Platelets adhesion and activation were suppressed significantly (97% for 4 mA NiTi) and hemolysis rate was decreased by at least 57% after Hf implantation. Modified surface composition and morphology and decreased surface energy should be responsible for the improvement of cytocompatibility and hemocompatibility.

  6. A Study on Removal of Rare Earth Elements from U.S. Coal Byproducts by Ion Exchange

    NASA Astrophysics Data System (ADS)

    Rozelle, Peter L.; Khadilkar, Aditi B.; Pulati, Nuerxida; Soundarrajan, Nari; Klima, Mark S.; Mosser, Morgan M.; Miller, Charles E.; Pisupati, Sarma V.

    2016-03-01

    Rare earth elements are known to occur in low concentrations in U.S. coals and coal byproducts. These low concentrations may make rare earth element recovery from these materials unattractive, using only physical separation techniques. However, given the significant production of rare earths through ion exchange extraction in China, two U.S. coal byproducts were examined for ion extraction, using ammonium sulfate, an ionic liquid, and a deep eutectic solvent as lixiviants. Extraction of rare earth elements in each case produced high recoveries of rare earth elements to the solution. This suggests that in at least the cases of the materials examined, U.S. coal byproducts may be technically suitable as REE ores. More work is required to establish economic suitability.

  7. Environmental risk of particulate and soluble platinum group elements released from gasoline and diesel engine catalytic converters.

    PubMed

    Moldovan, M; Palacios, M A; Gómez, M M; Morrison, G; Rauch, S; McLeod, C; Ma, R; Caroli, S; Alimonti, A; Petrucci, F; Bocca, B; Schramel, P; Zischka, M; Pettersson, C; Wass, U; Luna, M; Saenz, J C; Santamaría, J

    2002-09-16

    A comparison of platinum-group element (PGE) emission between gasoline and diesel engine catalytic converters is reported within this work. Whole raw exhaust fumes from four catalysts of three different types were examined during their useful lifetime, from fresh to 80,000 km. Two were gasoline engine catalysts (Pt-Pd-Rh and Pd-Rh), while the other two were diesel engine catalysts (Pt). Samples were collected following the 91441 EUDC driving cycle for light-duty vehicle testing, and the sample collection device used allowed differentiation between the particulate and soluble fractions, the latter being the most relevant from an environmental point of view. Analyses were performed by inductively coupled plasma-mass spectrometry (ICP-MS) (quadrupole and high resolution), and special attention was paid to the control of spectral interference, especially in the case of Pd and Rh. The results obtained show that, for fresh catalysts, the release of particulate PGE through car exhaust fumes does not follow any particular trend, with a wide range (one-two orders of magnitude) for the content of noble metals emitted. The samples collected from 30,000-80,000 km present a more homogeneous PGE release for all catalysts studied. A decrease of approximately one order of magnitude is observed with respect to the release from fresh catalysts, except in the case of the diesel engine catalyst, for which PGE emission continued to be higher than in the case of gasoline engines. The fraction of soluble PGE was found to represent less than 10% of the total amount released from fresh catalysts. For aged catalysts, the figures are significantly higher, especially for Pd and Rh. Particulate PGE can be considered as virtually biologically inert, while soluble PGE forms can represent an environmental risk due to their bioavailability, which leads them to accumulate in the environment.

  8. Deformation and stress distribution of the human foot after plantar ligaments release: a cadaveric study and finite element analysis.

    PubMed

    Liang, Jun; Yang, Yunfeng; Yu, Guangrong; Niu, Wenxin; Wang, Yubin

    2011-03-01

    The majority of foot deformities are related to arch collapse or instability, especially the longitudinal arch. Although the relationship between the plantar fascia and arch height has been previously investigated, the stress distribution remains unclear. The aim of this study was to explore the role of the plantar ligaments in foot arch biomechanics. We constructed a geometrical detailed three-dimensional (3-D) finite element (FE) model of the human foot and ankle from computer tomography images. The model comprised the majority of joints in the foot as well as bone segments, major ligaments, and plantar soft tissue. Release of the plantar fascia and other ligaments was simulated to evaluate the corresponding biomechanical effects on load distribution of the bony and ligamentous structures. These intrinsic ligaments of the foot arch were sectioned to simulate different pathologic situations of injury to the plantar ligaments, and to explore bone segment displacement and stress distribution. The validity of the 3-D FE model was verified by comparing results with experimentally measured data via the displacement and von Mise stress of each bone segment. Plantar fascia release decreased arch height, but did not cause total collapse of the foot arch. The longitudinal foot arch was lost when all the four major plantar ligaments were sectioned simultaneously. Plantar fascia release was compromised by increased strain applied to the plantar ligaments and intensified stress in the midfoot and metatarsal bones. Load redistribution among the centralized metatarsal bones and focal stress relief at the calcaneal insertion were predicted. The 3-D FE model indicated that plantar fascia release may provide relief of focal stress and associated heel pain. However, these operative procedures may pose a risk to arch stability and clinically may produce dorsolateral midfoot pain. The initial strategy for treating plantar fasciitis should be non-operative.

  9. Elemental ratios and the uptake and release of nutrients by phytoplankton and bacteria in three lakes of the Canadian shield.

    PubMed

    Elser, J J; Chrzanowski, T H; Sterner, R W; Schampel, J H; Foster, D K

    1995-03-01

    The dynamics of carbon (C), nitrogen (N), and phosphorus (P), elemental ratios, and dark uptake/release of N and P in bacterial and phytoplankton size fractions were studied during summer 1992 in three lakes of contrasting food web structure and trophic status (L240, L110, L227). We wished to determine if phytoplankton and bacteria differed in their elemental characteristics and to evaluate whether the functional role of bacteria in nutrient cycling (i.e., as sink or source) depended on bacterial elemental characteristics. Bacterial contributions to total suspended particulate material and to fluxes of nutrients in the dark were substantial and varied for different elements. This indicated that some techniques for assaying phytoplankton physiological condition are compromised by bacterial contributions. C/N ratios were generally less variable than C/P and N/P ratios. Both elemental ratios and biomass-normalized N and P flux indicated that phytoplankton growth in each lake was predominantly P-limited, although in L227 these data reflect the dominance of N-fixing cyanobacteria, and N was likely limiting early in the sampling season. In L227, phytoplankton N/P ratio and biomass-normalized N flux were negatively correlated, indicating that flux data were likely a reasonable measure of the N status of the phytoplankton. However, for L227 phytoplankton, P-flux per unit biomass was a hyperbolic function of N/P, suggesting that the dominant L227 cyanobacteria have a limited uptake and storage capacity and that P-flux per unit biomass may not be a good gauge of the P-limitation status of phytoplankton in this situation. Examination of N-flux data in the bacterial size fraction relative to the N/P ratio of the bacteria revealed a threshold N/P ratio (∼22:1 N/P, by atoms), below which, bacteria took up and sequestered added N, and above which, N was released. Thus, the functional role of bacteria in N cycling in these ecosystems depended on their N/P stoichiometry.

  10. Co-operative action of calcium ions in dopamine release from rat brain synaptosomes.

    PubMed Central

    Nachshen, D A; Sanchez-Armass, S

    1987-01-01

    1. The release of [3H]dopamine from isolated presynaptic nerve terminals (synaptosomes) prepared from rat striata was measured as a function of the external Ca2+ concentration ([Ca2+]o). 2. In synaptosomes depolarized by the addition of 50 mM-K+, release of [3H]dopamine increased in a highly non-linear manner with [Ca2+]o. The release could be described as a third power function of [Ca2+]o. 3. Both 45Ca2+ influx and the change in the free cytosolic Ca2+ concentration ([Ca2+]i, measured with the fluorescent Ca2+ indicator fura-2) that were evoked by depolarization increased in a linear manner with [Ca2+]o. 4. These results suggest that non-linearity in the [Ca2+]o dependence of transmitter release originates in a co-operative relation between [Ca2+]i and exocytosis. PMID:3656180

  11. Inhibition of trace element release during Fe(II)-activated recrystallization of Al-, Cr-, and Sn-substituted goethite and hematite.

    PubMed

    Frierdich, Andrew J; Scherer, Michelle M; Bachman, Jonathan E; Engelhard, Mark H; Rapponotti, Brett W; Catalano, Jeffrey G

    2012-09-18

    Aqueous Fe(II) reacts with Fe(III) oxides by coupled electron transfer and atom exchange (ETAE) resulting in mineral recrystallization, contaminant reduction, and trace element cycling. Previous studies of Fe(II)-Fe(III) ETAE have explored the reactivity of either pure iron oxide phases or those containing small quantities of soluble trace elements. Naturally occurring iron oxides, however, contain substantial quantities of insoluble impurities (e.g., Al) which are known to affect the chemical properties of such minerals. Here we explore the effect of Al(III), Cr(III), and Sn(IV) substitution (1-8 mol %) on trace element release from Ni(II)-substituted goethite and Zn(II)-substituted hematite during reaction with aqueous Fe(II). Fe(II)-activated trace element release is substantially inhibited from both minerals when an insoluble element is cosubstituted into the structure, and the total amount of release decreases exponentially with increasing cosubstituent. The limited changes in surface composition that occur following reaction with Fe(II) indicate that Al, Cr, and Sn do not exsolve from the structure and that Ni and Zn released to solution originate primarily from the bulk rather than the particle exterior (upper ~3 nm). Incorporation of Al into goethite substantially decreases the amount of iron atom exchange with aqueous Fe(II) and, consequently, the amount of Ni release from the structure. This implies that trace element release inhibition caused by substituting insoluble elements results from a decrease in the amount of mineral recrystallization. These results suggest that naturally occurring iron oxides containing insoluble elements are less susceptible to Fe(II)-activated recrystallization and exhibit a greater retention of trace elements and contaminants than pure mineral phases.

  12. Inhibition of trace element release during Fe(II)-activated recrystallization of Al-, Cr-, and Sn-substituted goethite and hematite

    SciTech Connect

    Frierdich, Andrew J.; Scherer, M.; Bachman, Jonathan E.; Engelhard, Mark H.; Rapponotti, Brett W.; Catalano, Jeffrey G.

    2012-09-18

    Aqueous Fe(II) reacts with Fe(III) oxides by coupled electron transfer and atom exchange (ETAE) resulting in mineral recrystallization, contaminant reduction, and trace element cycling. Previous studies of Fe(II)-Fe(III) ETAE have explored the reactivity of either pure iron oxide phases or those containing small quantities of soluble trace elements. Naturally occurring iron oxides, however, contain substantial quantities of insoluble impurities (e.g., Al) which are known to affect the chemical properties of such minerals. Here we explore the effect of Al(III), Cr(III), and Sn(IV) substitution on trace element release from Ni(II)-substituted goethite and Zn(II)-substituted hematite during reaction with aqueous Fe(II). Fe(II)-activated trace element release is substantially inhibited from both minerals when an insoluble element is co-substituted into the structure, and the total amount of release decreases exponentially with increasing co substituent. The limited changes in surface composition that occur following reaction with Fe(II) indicate that Al, Cr, and Sn do not exsolve from the structure and that Ni and Zn released to solution originate primarily from the bulk rather than the particle exterior (upper ~3 nm). Incorporation of Al into goethite substantially decreases the amount of iron atom exchange with aqueous Fe(II) and, consequently, the amount of Ni release from the structure. This implies that trace element release inhibition caused by substituting insoluble elements results from a decrease in the amount of mineral recrystallization. These results suggest that naturally occurring iron oxides containing insoluble elements are less susceptible to Fe(II)-activated recrystallization and exhibit a greater retention of trace elements and contaminants than pure mineral phases.

  13. Fluoride coatings on orthodontic wire for controlled release of fluorine ion.

    PubMed

    Lee, Su-Hee; Kim, Hae-Won; Kong, Young-Min; Kim, Hyoun-Ee; Lee, Sung-Ho; Chang, Young-Il

    2005-10-01

    The purpose of this study was to develop a new method of releasing fluorine in a controlled manner for applications in the field of orthodontic Ti-based wire, namely the coating of fluorides on Ti. Thin films of two fluoride compounds, CaF(2) and MgF(2), were coated on Ti via the electron-beam evaporation method. The fluorine was released rapidly from the as-deposited MgF(2) coating within a short period(,) and then the release rate slowed down. When the MgF(2) coating was heat treated, this initial burst effect was decreased, but a significant amount of cracks were generated. On the other hand, in the case of the as-deposited CaF(2) coating, fluorine was released linearly for the entire period, without an initial burst. In the heat-treated CaF(2) coatings the trend was similarly observed. The linear fluorine release from the CaF(2) coatings, even in the as-deposited state, was attributed to the high degree of crystallinity of the coatings. A preliminary cell test showed favorable cell viability on both the fluoride coatings. Given their sustained and controlled fluorine release, these fluoride coatings, particularly CaF(2), are suggested to be potentially useful in the field of orthodontic Ti-based wire.

  14. Novel CaF2 Nanocomposite with High Strength and Fluoride Ion Release

    PubMed Central

    Xu, H.H.K.; Moreau, J.L.; Sun, L.; Chow, L.C.

    2010-01-01

    Secondary caries and restoration fracture remain common problems in dentistry. This study tested the hypothesis that combining nano-CaF2 and glass fillers would yield nanocomposites with high mechanical properties and F release. Novel CaF2 nanoparticles (56-nm) were synthesized via spray-drying and incorporated into resin. F release increased with increasing the nano-CaF2 content, or with decreasing pH (p < 0.05). F-release rates at 70-84 days were 1.13 µg/(cm2·day) and 0.50 µg/(cm2·day) for nanocomposites containing 30% and 20% nano-CaF2, respectively. They matched the 0.65 µg/(cm2·day) of resin-modified glass ionomer (p > 0.1). The nanocomposites had flexural strengths of 70-120 MPa, after 84-day immersion at pH 4, pH 5.5, and pH 7. These strengths were nearly three-fold that of resin-modified glass ionomer, and matched/exceeded a composite with little F release. In summary, novel CaF2 nanoparticles produced high F release at low filler levels, thereby making room in resin for reinforcement glass. This yielded nanocomposites with high F-release and stress-bearing properties, which may help reduce secondary caries and restoration fracture. PMID:20439933

  15. Evaluation of effect of galvanic corrosion between nickel-chromium metal and titanium on ion release and cell toxicity

    PubMed Central

    Choi, Jung-Yun

    2015-01-01

    PURPOSE The purpose of this study was to evaluate cell toxicity due to ion release caused by galvanic corrosion as a result of contact between base metal and titanium. MATERIALS AND METHODS It was hypothesized that Nickel (Ni)-Chromium (Cr) alloys with different compositions possess different corrosion resistances when contacted with titanium abutment, and therefore in this study, specimens (10×10×1.5 mm) were fabricated using commercial pure titanium and 3 different types of Ni-Cr alloys (T3, Tilite, Bella bond plus) commonly used for metal ceramic restorations. The specimens were divided into 6 groups according to the composition of Ni-Cr alloy and contact with titanium. The experimental groups were in direct contact with titanium and the control groups were not. After the samples were immersed in the culture medium - Dulbecco's modified Eagle's medium[DMEM] for 48 hours, the released metal ions were detected using inductively coupled plasma mass spectrometer (ICP-MS) and analyzed by the Kruskal-Wallis and Mann-Whitney test (P<.05). Mouse L-929 fibroblast cells were used for cell toxicity evaluation. The cell toxicity of specimens was measured by the 3-{4,5-dimethylthiazol-2yl}-2,5-diphenyltetrazolium bromide (MTT) test. Results of MTT assay were statistically analyzed by the two-way ANOVA test (P<.05). Post-hoc multiple comparisons were conducted using Tukey's tests. RESULTS The amount of metal ions released by galvanic corrosion due to contact between the base metal alloy and titanium was increased in all of the specimens. In the cytotoxicity test, the two-way ANOVA showed a significant effect of the alloy type and galvanic corrosion for cytotoxicity (P<.001). The relative cell growth rate (RGR) was decreased further on the groups in contact with titanium (P<.05). CONCLUSION The release of metal ions was increased by galvanic corrosion due to contact between base metal and titanium, and it can cause adverse effects on the tissue around the implant by inducing

  16. Real-Time Monitoring of Potassium Ion Release Due to Apoptosis with Cell-Based Transparent-Gate Transistor

    NASA Astrophysics Data System (ADS)

    Sakata, Toshiya; Makino, Izumi; Sugimoto, Haruyo

    2012-01-01

    We monitored programmed cell death (apoptosis) in a real-time, direct and noninvasive manner using a cell-based transparent-gate transistor (TGT). Indium-tin-oxide (ITO) was utilized as a gate material, because cultured cells could be easily observed by microscopy due to its transparency. After induction of apoptosis on the cell-based TGT, the change of threshold voltage decreased gradually, which resulted from potassium ion release caused by apoptosis. The morphological change of apoptotic cells was simultaneously observed by the inverted microscopy. The platform based on the cell-based TGT is suitable for a simultaneous analysis system to realize subjective and objective evaluation of cell activities.

  17. Mineralogy and the release of trace elements from slag from the Hegeler Zinc smelter, Illinois (USA)

    USGS Publications Warehouse

    Piatak, N.M.; Seal, R.R.

    2010-01-01

    Slag from the former Hegeler Zn-smelting facility in Illinois (USA) is mainly composed of spinifex Ca-rich plagioclase, fine-grained dendritic or coarse-grained subhedral to anhedral clinopyroxenes, euhedral to subhedral spinels, spherical blebs of Fe sulfides, silicate glass, and less commonly fayalitic olivine. Mullite and quartz were also identified in one sample as representing remnants of the furnace lining. Secondary phases such as goethite, hematite and gypsum are significant in some samples and reflect surficial weathering of the dump piles or represent byproducts of roasting. A relatively rare Zn-rich material contains anhedral willemite, subhedral gahnite, massive zincite, hardystonite and a Zn sulfate (brianyoungite), among other phases, and likely represents the molten content of the smelting furnace before Zn extraction. The bulk major-element chemistry of most slag samples is dominated by SiO2, Al2O3, Fe2O3 and CaO. The bulk composition of the slag suggests a high viscosity of the melt and the mineralogy suggests a high silica content of the melt. Bulk slag trace-element chemistry shows that the dominant metal is Zn with >28.4 wt.% in the Zn-rich material and between 212 and 14,900 mg/kg in the other slags. The concentrations of other trace elements reach the following: 45 mg/kg As, 1170 mg/kg Ba, 191 mg/kg Cd, 242 mg/kg Co, 103 mg/kg Cr, 6360 mg/kg Cu, 107 mg/kg Ni, and 711 mg/kg Pb. Zinc, as the dominant metal in the slags, is likely the most environmentally significant metal in these samples; Cd, Cu, and Pb are also of concern and their concentrations exceed US Environmental Protection Agency preliminary remediation goals for residential soils. Spinel was found to be the dominant concentrator of Zn for samples containing significant Zn (>1 wt.%); the silicate glass also contained relatively high concentrations of Zn compared to other phases. Zinc partitioned into the silicates and oxides in these samples is generally more resistant to weathering

  18. Synthesis, characterization and application of ion exchange resin as a slow-release fertilizer for wheat cultivation in space

    NASA Astrophysics Data System (ADS)

    Li, Bowei; Dong, Chen; Chu, Zhengpei; Zhang, Weizhe; Wang, Minjuan; Liu, Hong; Xie, Beizhen

    2016-10-01

    In addition to the bio-regenerative air revitalization, water recycling and waste management systems and their associated challenges, enhancing the crop yield with less fertilizer input for sustainable food production in space is also a challenge that needs to be overcome. The purpose of this study is to investigate the feasibility of applying ion exchange resin as a slow-release fertilizer for wheat cultivation in space. Strong-acid cationic exchange resins and weak-base anion exchange resins soaked in 1X, 5X, 10X and 15X Hoagland nutrient solutions, respectively, were used as fertilizers in clinoptilolite to cultivate wheat plants, and the morphological and physiological characteristics of the wheat plants were studied and compared with that of the wheat planted in vermiculite and nutrient solutions. The results showed that more ions were attached on the surface of the ion exchange resins as the solution concentration increased. After 14 days, the fresh weight of wheat planted in the ion exchange resin-clinoptilolite (IER-clinoptilolite) treated with 10X and 15X solutions were 190% and 192% higher than that of wheat planted in nutrient solution with the same concentration. Chlorophyll content of wheat plants cultivated in the two kinds of solid medium is significantly higher than that of liquid cultivation. The lowest peroxidase (POD) activity and malondialdehyde (MDA) contents of wheat plants cultivated in the IER-clinoptilolite appeared on the 14th day. According to all the experimental data, it's promising to produce slow-release nutrient fertilizer by using strong-acid cationic exchange resins and weak-base anion exchange resins for wheat cultivation in space.

  19. Magnetic properties and element concentrations in lichens exposed to airborne pollutants released during cement production.

    PubMed

    Paoli, Luca; Winkler, Aldo; Guttová, Anna; Sagnotti, Leonardo; Grassi, Alice; Lackovičová, Anna; Senko, Dušan; Loppi, Stefano

    2016-02-15

    The content of selected elements (Al, As, Ca, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, S, Ti, V and Zn) was measured in samples of the lichen Evernia prunastri exposed for 30, 90 and 180 days around a cement mill, limestone and basalt quarries and urban and agricultural areas in SW Slovakia. Lichens transplanted around the investigated quarries and the cement mill rapidly (30 days) reflected the deposition of dust-associated elements, namely Ca (at the cement mill and the limestone quarry) and Fe, Ti and V (around the cement mill and the basalt quarry), and their content remained significantly higher throughout the whole period (30-180 days) with respect to the surrounding environment. Airborne pollutants (such as S) progressively increased in the study area from 30 to 180 days. The magnetic properties of lichen transplants exposed for 180 days have been characterized and compared with those of native lichens (Xanthoria parietina) and neighbouring bark, soil and rock samples, in order to test the suitability of native and transplanted samples as air pollution magnetic biomonitors. The magnetic mineralogy was homogeneous in all samples, with the exception of the samples from the basalt quarry. The transplants showed excellent correlations between the saturation remanent magnetization (Mrs) and the content of Fe. Native samples had a similar magnetic signature, but the values of the concentration-dependent magnetic parameters were up to two orders of magnitude higher, reflecting higher concentrations of magnetic particles. The concentrations of As, Ca and Cr in lichens correlated with Mrs values after neglecting the samples from the basalt quarry, which showed distinct magnetic properties, suggesting the cement mill as a likely source. Conversely, Ti and Mn were mostly (but not exclusively) associated with dust from the basalt quarry. It is suggested that the natural geological characteristics of the substrate may strongly affect the magnetic properties of lichen thalli

  20. Nickel Ion Release from Three Types of Nickel-titanium-based Orthodontic Archwires in the As-received State and After Oral Simulation

    PubMed Central

    Ramazanzadeh, Barat Ali; Ahrari, Farzaneh; Sabzevari, Berahman; Habibi, Samaneh

    2014-01-01

    Background and aims. This study aimed to investigate release of nickel ion from three types of nickel-titanium-based wires in the as-received state and after immersion in a simulated oral environment. Materials and methods. Forty specimens from each of the single-strand NiTi (Rematitan "Lite"), multi-strand NiTi (SPEED Supercable) and Copper NiTi (Damon Copper NiTi) were selected. Twenty specimens from each type were used in the as-received state and the others were kept in deflected state at 37ºC for 2 months followed by autoclave sterilization. The as-received and recycled wire specimens were immersed in glass bottles containing 1.8 mL of artificial saliva for 28 days and the amount of nickel ion released into the electrolyte was determined using atomic absorption spectrophotometry. Results. The single-strand NiTi released the highest quantity of nickel ion in the as-received state and the multi-strand NiTi showed the highest ion release after oral simulation. The quantity of nickelion released from Damon Copper NiTi was the lowest in both conditions. Oral simulation followed by sterilization did not have a significant influence on nickel ion release from multi-strand NiTi and Damon Copper NiTi wires, but single-strand NiTi released statistically lower quantities of nickel ion after oral simulation. Conclusion. The multi-strand nature of Supercable did not enhance the potential of corrosion after immersion in the simulated oral environment. In vitro use of nickel-titanium-based archwires followed by sterilization did not significantly increase the amount of nickel ion released from these wires. PMID:25093049

  1. Impact of rice cultivar and organ on elemental composition of phytoliths and the release of bio-available silicon

    PubMed Central

    Li, Zimin; Song, Zhaoliang; Cornelis, Jean-Thomas

    2014-01-01

    The continental bio-cycling of silicon (Si) plays a key role in global Si cycle and as such partly controls global carbon (C) budget through nutrition of marine and terrestrial biota, accumulation of phytolith-occluded organic carbon (PhytOC) and weathering of silicate minerals. Despite the key role of elemental composition of phytoliths on their solubility in soils, the impact of plant cultivar and organ on the elemental composition of phytoliths in Si high-accumulator plants, such as rice (Oryza sativa) is not yet fully understood. Here we show that rice cultivar significantly impacts the elemental composition of phytoliths (Si, Al, Fe, and C) in different organs of the shoot system (grains, sheath, leaf and stem). The amount of occluded OC within phytoliths is affected by contents of Si, Al, and Fe in plants, while independent of the element composition of phytoliths. Our data document, for different cultivars, higher bio-available Si release from phytoliths of leaves and sheaths, which are characterized by higher enrichment with Al and Fe (i.e., lower Si/Al and Si/Fe ratios), compared to grains and stems. We indicate that phytolith solubility in soils may be controlled by rice cultivar and type of organs. Our results highlight that the role of the morphology, the hydration rate and the chemical composition in the solubility of phytoliths and the kinetic release of Si in soil solution needs to be studied further. This is central to a better understanding of the impact of soil amendment with different plant organs and cultivars on soil OC stock and on the delivery of dissolved Si as we show that sheath and leaf rice organs are both characterized by higher content of OC occluded in phytolith and higher phytolith solubility compared to grains and stems. Our study shows the importance of studying the impact of the agro-management on the evolution of sinks and sources of Si and C in soils used for Si-high accumulator plants. PMID:25346741

  2. Utilizing environmental friendly iron as a substitution element in spinel structured cathode materials for safer high energy lithium-ion batteries

    DOE PAGES

    Hu, Enyuan; Bak, Seong -Min; Liu, Yijin; ...

    2015-12-03

    Suppressing oxygen release from lithium ion battery cathodes during heating is a critical issue for the improvement of the battery safety characteristics because oxygen can exothermically react with the flammable electrolyte and cause thermal runaway. Previous studies have shown that oxygen release can be reduced by the migration of transition metal cations from octahedral sites to tetrahedral sites during heating. Such site-preferred migration is determined by the electronic structure of cations. In addition, taking advantage of the unique electronic structure of the environmental friendly Fe, this is selected as substitution element in a high energy density material LiNi0.5Mn1.5O4 to improvemore » the thermal stability. The optimized LiNi0.33Mn1.33Fe0.33O4 material shows significantly improved thermal stability compared with the unsubstituted one, demonstrated by no observed oxygen release at temperatures as high as 500°C. Due to the electrochemical contribution of Fe, the high energy density feature of LiNi0.5Mn1.5O4 is well preserved.« less

  3. Utilizing environmental friendly iron as a substitution element in spinel structured cathode materials for safer high energy lithium-ion batteries

    SciTech Connect

    Hu, Enyuan; Bak, Seong -Min; Liu, Yijin; Liu, Jue; Yu, Xiqian; Zhou, Yong -Ning; Zhou, Jigang; Khalifah, Peter; Ariyoshi, Kingo; Nam, Kyung -Wan; Yang, Xiao -Qing

    2015-12-03

    Suppressing oxygen release from lithium ion battery cathodes during heating is a critical issue for the improvement of the battery safety characteristics because oxygen can exothermically react with the flammable electrolyte and cause thermal runaway. Previous studies have shown that oxygen release can be reduced by the migration of transition metal cations from octahedral sites to tetrahedral sites during heating. Such site-preferred migration is determined by the electronic structure of cations. In addition, taking advantage of the unique electronic structure of the environmental friendly Fe, this is selected as substitution element in a high energy density material LiNi0.5Mn1.5O4 to improve the thermal stability. The optimized LiNi0.33Mn1.33Fe0.33O4 material shows significantly improved thermal stability compared with the unsubstituted one, demonstrated by no observed oxygen release at temperatures as high as 500°C. Due to the electrochemical contribution of Fe, the high energy density feature of LiNi0.5Mn1.5O4 is well preserved.

  4. A Stabilized Finite Element Method for Modified Poisson-Nernst-Planck Equations to Determine Ion Flow Through a Nanopore.

    PubMed

    Chaudhry, Jehanzeb Hameed; Comer, Jeffrey; Aksimentiev, Aleksei; Olson, Luke N

    2014-01-01

    The conventional Poisson-Nernst-Planck equations do not account for the finite size of ions explicitly. This leads to solutions featuring unrealistically high ionic concentrations in the regions subject to external potentials, in particular, near highly charged surfaces. A modified form of the Poisson-Nernst-Planck equations accounts for steric effects and results in solutions with finite ion concentrations. Here, we evaluate numerical methods for solving the modified Poisson-Nernst-Planck equations by modeling electric field-driven transport of ions through a nanopore. We describe a novel, robust finite element solver that combines the applications of the Newton's method to the nonlinear Galerkin form of the equations, augmented with stabilization terms to appropriately handle the drift-diffusion processes. To make direct comparison with particle-based simulations possible, our method is specifically designed to produce solutions under periodic boundary conditions and to conserve the number of ions in the solution domain. We test our finite element solver on a set of challenging numerical experiments that include calculations of the ion distribution in a volume confined between two charged plates, calculations of the ionic current though a nanopore subject to an external electric field, and modeling the effect of a DNA molecule on the ion concentration and nanopore current.

  5. Prospects for laser spectroscopy, ion chemistry and mobility measurements of superheavy elements in buffer-gas traps

    NASA Astrophysics Data System (ADS)

    Backe, H.; Lauth, W.; Block, M.; Laatiaoui, M.

    2015-12-01

    Laser spectroscopic methods are reviewed which are of potential interest for the investigation of atomic and ionic level structures of superheavy elements. The latter are defined here as the trans-fermium elements with Z > 100 for which no experimental atomic or ionic level structure information is known so far, and which cannot be bred in high flux nuclear power reactors via successive neutron capture. The principles of suitable laser spectroscopic methods are described, and illustrated by examples of real experiments. The addressed methods include single-ion spectroscopy in Paul traps, laser-induced fluorescence spectroscopy (LIF), radiation-detected optical pumping (RADOP), radioactive decay-detected resonance ionization spectroscopy (RADRIS), and ion-guide-detected resonance ionization spectroscopy (IGRIS). With the exception of the first all take advantage of a storage of the ions or atoms in so-called buffer-gas traps. The developed experimental methods can, in principle, also be employed for studying ion-chemical reactions with gas admixtures like O2 as well as for performing ion mobility measurements. Both provide complementary information on the electronic structure of superheavy ions. First attempts on this road of research are reviewed as well.

  6. Release of major elements from recycled concrete aggregates and geochemical modelling

    SciTech Connect

    Engelsen, Christian J. Sloot, Hans A. van der; Wibetoe, Grethe; Petkovic, Gordana; Stoltenberg-Hansson, Erik; Lund, Walter

    2009-05-15

    The pH dependent leaching characteristics were assessed for different types of recycled concrete aggregates, including real construction debris and crushed fresh concrete samples prepared in laboratory. Carbonation effects were identified from the characteristic pH dependent leaching patterns for the major constituents Al, Ca, Fe, Mg, Si and SO{sub 4}{sup 2-}. The original particle size ranges were different for the samples investigated and this factor influenced the cement paste content in the samples which in turn controlled the leachable contents. Cement paste contents for concrete samples with fine particle size fractions (0-4 mm) were found to be higher than the originally present amount in the hardened concrete. Geochemical speciation modelling was applied over the entire pH range using the speciation and transport modelling framework ORCHESTRA, for which mineral saturation, solution speciation and sorption processes can be calculated based on equilibrium models and thermodynamic data. The simulated equilibrium concentrations by this model agreed well with the respective measured concentrations. The main differences between the fresh and aged materials were quantified, described and predicted by the ORCHESTRA. Solubility controlling mineral phase assemblages were calculated by the model as function of pH. Cement hydrate phases such as calcium silicate hydrate, calcium aluminate hydrate (AFm and AFt) and hydrogarnet were predominating at the material pH. The concentration of carboaluminates was found to be strongly dependent on the available carbonates in the samples. As the pH was decreased these phases decomposed to more soluble species or precipitates were formed including iron- and aluminium hydroxides, wairakite and amorphous silica. In the most acid region most phases dissolved, and the major elements were approaching maximum leachability, which was determined by the amount of cement paste.

  7. Objective Assessment of an Ionic Footbath (IonCleanse): Testing Its Ability to Remove Potentially Toxic Elements from the Body

    PubMed Central

    Kennedy, Deborah A.; Cooley, Kieran; Einarson, Thomas R.; Seely, Dugald

    2012-01-01

    Ionic footbaths are often used in holistic health centres and spas to aid in detoxification; however, claims that these machines eliminate toxins from the body have not been rigorously evaluated. In this proof-of-principle study, we sought to measure the release of potentially toxic elements from ionic footbaths into distilled and tap water with and without feet. Water samples were collected and analyzed following 30-minute ionic footbath sessions without feet using both distilled (n = 1) and tap water (n = 6) and following four ionic footbaths using tap water (once/week for 4 weeks) in six healthy participants. Urine collection samples were analyzed at four points during the study. Hair samples were analyzed for element concentrations at baseline and study conclusion. Contrary to claims made for the machine, there does not appear to be any specific induction of toxic element release through the feet when running the machine according to specifications. PMID:22174728

  8. Oxidation Resistance of Fe80Cr20 Alloys Treated by Rare Earth Element Ion Implantation

    NASA Astrophysics Data System (ADS)

    Sebayang, Darwin; Khaerudini, Deni S.; Saryanto, H.; Hasan, Sulaiman; Othman, M. A.; Untoro, Puji

    2011-10-01

    The oxidation behaviour of newly developed process of Fe80Cr20 alloy was studied as a function of temperature in the range 1173-1273 K for up to 100 h in flowing air, which corresponds to the Solid Oxide Fuel Cell (SOFC) environment operating conditions. The effects of rare earth element implantation and depth profile on the oxidation behaviour of specimens were analyzed based on oxide morphology and microstructure. Characterisation of the oxide phase products after oxidation was made by X-ray diffraction (XRD). The surface morphology of oxide scales was examined using the scanning electronic microscope (SEM) with energy-dispersive X-ray analysis (EDX). The rate constant of thermal oxidation was determined using Wagner method. Experimental results show that the specimens implanted with lanthanum have remarkably enhanced the oxidation resistance. The oxidation test indicates that the newly developed process of Fe80Cr20 implantation with lanthanum ions exhibit considerably greater improvement in the oxidation resistance compared to the specimens implanted with titanium. The newly developed process of Fe80Cr20 milled for 60h show better oxidation resistance compared to specimens milled for 40h.

  9. Silver release from nanocomposite Ag/alginate hydrogels in the presence of chloride ions: experimental results and mathematical modeling

    NASA Astrophysics Data System (ADS)

    Kostic, Danijela; Vidovic, Srđan; Obradovic, Bojana

    2016-03-01

    A stepwise experimental and mathematical modeling approach was used to assess silver release from nanocomposite Ag/alginate microbeads in wet and dried forms into water and into normal saline solution chosen as a simplified model for certain biological fluids (e.g., blood plasma, wound exudates, sweat, etc). Three phenomena were connected and mathematically described: diffusion of silver nanoparticles (AgNPs) within the alginate hydrogel, AgNP oxidation/dissolution and reaction with chloride ions, and diffusion of the resultant silver-chloride species. Mathematical modeling results agreed well with the experimental data with the AgNP diffusion coefficient estimated as 1.3 × 10-18 m2 s-1, while the first-order kinetic rate constant of AgNP oxidation/dissolution and diffusivity of silver-chloride species were shown to be inversely related. In specific, rapid rehydration and swelling of dry Ag/alginate microbeads induced fast AgNP oxidation/dissolution reaction with Cl- and AgCl precipitation within the microbeads with the lowest diffusivity of silver-chloride species compared to wet microbeads in normal saline. The proposed mathematical model provided an insight into the phenomena related to silver release from nanocomposite Ca-alginate hydrogels relevant for use of antimicrobial devices and established, at the same time, a basis for further in-depth studies of AgNP interactions in hydrogels in the presence of chloride ions.

  10. Weight loss, ion release and initial mechanical properties of a binary calcium phosphate glass fibre/PCL composite.

    PubMed

    Ahmed, I; Parsons, A J; Palmer, G; Knowles, J C; Walker, G S; Rudd, C D

    2008-09-01

    Composites comprising a biodegradable polymeric matrix and a bioactive filler show considerable promise in the field of regenerative medicine, and could potentially serve as degradable bone fracture fixation devices, depending on the properties obtained. Therefore, glass fibres from a binary calcium phosphate (50P(2)O(5)+50CaO) glass were used to reinforce polycaprolactone, at two different volume fractions (V(f)). As-drawn, non-treated and heat-treated fibres were assessed. Weight loss, ion release and the initial mechanical properties of the fibres and composites produced have been investigated. Single fibre tensile testing revealed a fibre strength of 474MPa and a tensile modulus of 44GPa. Weibull analysis suggested a scale value of 524. The composites yielded flexural strength and modulus of up to 30MPa and 2.5GPa, respectively. These values are comparable with human trabecular bone. An 8% mass loss was seen for the lower V(f) composite, whereas for the two higher V(f) composites an approximate 20% mass loss was observed over the course of the 5week study. A plateau in the degradation profile at 350h indicated that fibre dissolution was complete at this interval. This assertion was further supported via ion release studies. The leaching of fibres from the composite created a porous structure, including continuous channels within the polymer matrix. This offers further scope for tailoring scaffold development, as cells from the surrounding tissue may be induced to migrate into the resulting porous matrix.

  11. Release of extracellular purines from plant roots and effect on ion fluxes.

    PubMed

    Dark, Adeeba; Demidchik, Vadim; Richards, Siân L; Shabala, Sergey; Davies, Julia M

    2011-11-01

    Extracellular purine nucleotides appear capable of regulating plant development, defence and stress responses by acting in part as agonists of plasma membrane calcium channels. Factors stimulating ATP release include wounding, osmotic stress and elicitors. Here we show that exogenous abscisic acid and L-glutamate can also cause ATP accumulation around Arabidopsis thaliana roots. Release of ADP from root epidermis would trigger ionotropic receptor-like activity in the plasma membrane, resulting in transient elevation of cytosolic free calcium. Root epidermal protoplasts (expressing aequorin as a cytosolic free calcium reporter) can support an extracellular ADP-induced cytosolic calcium elevation in the presence of an extracellular reductant. This confirms that ADP could elicit calcium-based responses distinct to those of ATP, which have been shown previously to involve production of extracellular reactive oxygen species.

  12. Price to be paid for two-metal catalysis: magnesium ions that accelerate chemistry unavoidably limit product release from a protein kinase.

    PubMed

    Jacobsen, Douglas M; Bao, Zhao-Qin; O'Brien, Patrick; Brooks, Charles L; Young, Matthew A

    2012-09-19

    Incorporation of divalent metal ions into an active site is a fundamental catalytic tool used by diverse enzymes. Divalent cations are used by protein kinases to both stabilize ATP binding and accelerate chemistry. Kinetic analysis establishes that Cyclin-dependent kinase 2 (CDK2) requires simultaneous binding of two Mg(2+) ions for catalysis of phosphoryl transfer. This tool, however, comes with a price: the rate-acceleration effects are opposed by an unavoidable rate-limiting consequence of the use of two Mg(2+) ions by CDK2. The essential metal ions stabilize ADP product binding and limit the overall rate of the reaction. We demonstrate that product release is rate limiting for activated CDK2 and evaluate the effects of the two catalytically essential Mg(2+) ions on the stability of the ADP product within the active site. We present two new crystal structures of CDK2 bound to ADP showing how the phosphate groups can be coordinated by either one or two Mg(2+) ions, with the occupancy of one site in a weaker equilibrium. Molecular dynamics simulations indicate that ADP phosphate mobility is more restricted when ADP is coordinated by two Mg(2+) ions compared to one. The structural similarity between the rigid ADP·2Mg product and the cooperatively assembled transition state provides a mechanistic rational for the rate-limiting ADP release that is observed. We demonstrate that although the simultaneous binding of two Mg(2+) ions is essential for efficient phosphoryl transfer, the presence of both Mg(2+) ions in the active site also cooperatively increases ADP affinity and opposes its release. Evolution of protein kinases must have involved careful tuning of the affinity for the second Mg(2+) ion in order to balance the needs to stabilize the chemical transition state and allow timely product release. The link between Mg(2+) site affinity and activity presents a chemical handle that may be used by regulatory factors as well as explain some mutational effects.

  13. Heavy-ion radiation induces both activation of multiple endogenous transposable elements and alterations in DNA methylation in rice

    NASA Astrophysics Data System (ADS)

    Zhang, Meng; Sun, Yeqing; Li, Xishan; Xiaolin, Cui; Li, Xiang

    2012-07-01

    Space radiation represents a complex environmental condition in which several interacting factors such as electron, neutron, proton, heavy-ion are involved, which may provoke stress responses and jeopardize genome integrity. Given the inherent property of epigenetic modifications to respond to intrinsic aswell as external perturbations, it is conceivable that epigenetic markers like DNA methylation and transposition may undergo alterations in response to space radiation. Cytosine DNA methylation plays important roles in maintaining genome stability and controlling gene expression. A predominant means for Transposable elements (TEs) to cause genetic instability is via their transpositional activation. To find the detailed molecular characterization of the nature of genomic changes induced by space radiation, the seeds of rice were exposed to 0.02, 0.2, 1, 2 and 20 Gy dose of ^{12}C heavy-ion radiation, respectively. We found that extensive alteration in both DNA methylation and gene expression occurred in rice plants after different dose of heavy-ion radiation. Here we shown that heavy-ion radiation has induced transposition of mPing and Tos17 in rice, which belong to distinct classes including the miniature inverted terminal repeat TEs (MITEs) and long-terminal repeat (LTR) retrotransposons, respectively. mPing and Tos17 mobility were found to correlate with cytosine methylation alteration detected by MSAP and genetic variation detected by AFLP. The result showed that at least in some cases transposition of TEs was associated with cytosine demethylation within the elements. Our results implicate that the heavy-ion radiation represents a potent mutagenic agent that can cause genomic instabilities by eliciting transposition of endogenous TEs in rice. Keywords: Heavy-ion radiation, DNA methylation, Transposable elements, mPing, Tos17

  14. MinION Analysis and Reference Consortium: Phase 1 data release and analysis.

    PubMed

    Ip, Camilla L C; Loose, Matthew; Tyson, John R; de Cesare, Mariateresa; Brown, Bonnie L; Jain, Miten; Leggett, Richard M; Eccles, David A; Zalunin, Vadim; Urban, John M; Piazza, Paolo; Bowden, Rory J; Paten, Benedict; Mwaigwisya, Solomon; Batty, Elizabeth M; Simpson, Jared T; Snutch, Terrance P; Birney, Ewan; Buck, David; Goodwin, Sara; Jansen, Hans J; O'Grady, Justin; Olsen, Hugh E

    2015-01-01

    The advent of a miniaturized DNA sequencing device with a high-throughput contextual sequencing capability embodies the next generation of large scale sequencing tools. The MinION™ Access Programme (MAP) was initiated by Oxford Nanopore Technologies™ in April 2014, giving public access to their USB-attached miniature sequencing device. The MinION Analysis and Reference Consortium (MARC) was formed by a subset of MAP participants, with the aim of evaluating and providing standard protocols and reference data to the community. Envisaged as a multi-phased project, this study provides the global community with the Phase 1 data from MARC, where the reproducibility of the performance of the MinION was evaluated at multiple sites. Five laboratories on two continents generated data using a control strain of Escherichia coli K-12, preparing and sequencing samples according to a revised ONT protocol. Here, we provide the details of the protocol used, along with a preliminary analysis of the characteristics of typical runs including the consistency, rate, volume and quality of data produced. Further analysis of the Phase 1 data presented here, and additional experiments in Phase 2 of E. coli from MARC are already underway to identify ways to improve and enhance MinION performance.

  15. MinION Analysis and Reference Consortium: Phase 1 data release and analysis

    PubMed Central

    Eccles, David A.; Zalunin, Vadim; Urban, John M.; Piazza, Paolo; Bowden, Rory J.; Paten, Benedict; Mwaigwisya, Solomon; Batty, Elizabeth M.; Simpson, Jared T.; Snutch, Terrance P.

    2015-01-01

    The advent of a miniaturized DNA sequencing device with a high-throughput contextual sequencing capability embodies the next generation of large scale sequencing tools. The MinION™ Access Programme (MAP) was initiated by Oxford Nanopore Technologies™ in April 2014, giving public access to their USB-attached miniature sequencing device. The MinION Analysis and Reference Consortium (MARC) was formed by a subset of MAP participants, with the aim of evaluating and providing standard protocols and reference data to the community. Envisaged as a multi-phased project, this study provides the global community with the Phase 1 data from MARC, where the reproducibility of the performance of the MinION was evaluated at multiple sites. Five laboratories on two continents generated data using a control strain of Escherichia coli K-12, preparing and sequencing samples according to a revised ONT protocol. Here, we provide the details of the protocol used, along with a preliminary analysis of the characteristics of typical runs including the consistency, rate, volume and quality of data produced. Further analysis of the Phase 1 data presented here, and additional experiments in Phase 2 of E. coli from MARC are already underway to identify ways to improve and enhance MinION performance. PMID:26834992

  16. Gas release of the dielectric coating of an anode and its effect on the characteristics of an ion diode with electron flux insulation by a radial magnetic field

    NASA Astrophysics Data System (ADS)

    Lopatin, V. S.; Stepanov, A. V.; Remnev, G. E.; Shamanin, V. I.; Veresov, A. E.

    2017-01-01

    Generation of an ion beam by an ion diode is accompanied by the release of gas from the surface of the dielectric coating of the anode. The magnitude of the pulse pressure of gas in the vacuum chamber depends on the type of the dielectric used and can reach 6 × 10-4-2 × 10-3 mm Hg. The magnitude of the limit vacuum chamber pressure at which ion beam parameters remain constant has been found. Characteristics of the ion beam current in the vacuum chamber pressure range of 2 × 10-4-1.3 × 10-3 mm Hg are presented.

  17. Quantifying element incorporation in multispecies biofilms using nanoscale secondary ion mass spectrometry image analysis

    SciTech Connect

    Renslow, Ryan S.; Lindemann, Stephen R.; Cole, Jessica K.; Zhu, Zihua; Anderton, Christopher R.

    2016-02-12

    EElucidating nutrient exchange in microbial communities is an important step in understanding the relationships between microbial systems and global biogeochemical cycles, but these communities are complex and the interspecies interactions that occur within them are not well understood. Phototrophic consortia are useful and relevant experimental systems to investigate such interactions as they are not only prevalent in the environment, but some are cultivable in vivo and amenable to controlled scientific experimentation. High spatial resolution secondary ion mass spectrometry (NanoSIMS) is a powerful tool capable of visualizing the metabolic activities of single cells within a biofilm, but quantitative analysis of the resulting data has typically been a manual process, resulting in a task that is both laborious and susceptible to human error. Here, we describe the creation and application of a semi-automated image-processing pipeline that can analyze NanoSIMS-generated data of phototrophic biofilms. The tool employs an image analysis process, which includes both elemental and morphological segmentation, producing a final segmented image that allows for discrimination between autotrophic and heterotrophic biomass, the detection of individual cyanobacterial filaments and heterotrophic cells, the quantification of isotopic incorporation of individual heterotrophic cells, and calculation of relevant population statistics. We demonstrate the functionality of the tool by using it to analyze the uptake of 15N provided as either nitrate or ammonium through the unicyanobacterial consortium UCC-O and imaged via NanoSIMS. We found that the degree of 15N incorporation by individual cells was highly variable when labeled with 15NH4 +, but much more even when biofilms were labeled with 15NO3-. In the 15NH4 +-amended biofilms, the heterotrophic distribution of 15N incorporation was highly skewed, with a large population showing moderate 15N incorporation and a small number of

  18. Quantifying element incorporation in multispecies biofilms using nanoscale secondary ion mass spectrometry image analysis.

    PubMed

    Renslow, Ryan S; Lindemann, Stephen R; Cole, Jessica K; Zhu, Zihua; Anderton, Christopher R

    2016-06-12

    Elucidating nutrient exchange in microbial communities is an important step in understanding the relationships between microbial systems and global biogeochemical cycles, but these communities are complex and the interspecies interactions that occur within them are not well understood. Phototrophic consortia are useful and relevant experimental systems to investigate such interactions as they are not only prevalent in the environment, but some are cultivable in vitro and amenable to controlled scientific experimentation. Nanoscale secondary ion mass spectrometry (NanoSIMS) is a powerful, high spatial resolution tool capable of visualizing the metabolic activities of single cells within a biofilm, but quantitative analysis of the resulting data has typically been a manual process, resulting in a task that is both laborious and susceptible to human error. Here, the authors describe the creation and application of a semiautomated image-processing pipeline that can analyze NanoSIMS-generated data, applied to phototrophic biofilms as an example. The tool employs an image analysis process, which includes both elemental and morphological segmentation, producing a final segmented image that allows for discrimination between autotrophic and heterotrophic biomass, the detection of individual cyanobacterial filaments and heterotrophic cells, the quantification of isotopic incorporation of individual heterotrophic cells, and calculation of relevant population statistics. The authors demonstrate the functionality of the tool by using it to analyze the uptake of (15)N provided as either nitrate or ammonium through the unicyanobacterial consortium UCC-O and imaged via NanoSIMS. The authors found that the degree of (15)N incorporation by individual cells was highly variable when labeled with (15)NH4 (+), but much more even when biofilms were labeled with (15)NO3 (-). In the (15)NH4 (+)-amended biofilms, the heterotrophic distribution of (15)N incorporation was highly skewed, with

  19. Stainless steel corrosion scale formed in reclaimed water: Characteristics, model for scale growth and metal element release.

    PubMed

    Cui, Yong; Liu, Shuming; Smith, Kate; Hu, Hongying; Tang, Fusheng; Li, Yuhong; Yu, Kanghua

    2016-10-01

    Stainless steels generally have extremely good corrosion resistance, but are still susceptible to pitting corrosion. As a result, corrosion scales can form on the surface of stainless steel after extended exposure to aggressive aqueous environments. Corrosion scales play an important role in affecting water quality. These research results showed that interior regions of stainless steel corrosion scales have a high percentage of chromium phases. We reveal the morphology, micro-structure and physicochemical characteristics of stainless steel corrosion scales. Stainless steel corrosion scale is identified as a podiform chromite deposit according to these characteristics, which is unlike deposit formed during iron corrosion. A conceptual model to explain the formation and growth of stainless steel corrosion scale is proposed based on its composition and structure. The scale growth process involves pitting corrosion on the stainless steel surface and the consecutive generation and homogeneous deposition of corrosion products, which is governed by a series of chemical and electrochemical reactions. This model shows the role of corrosion scales in the mechanism of iron and chromium release from pitting corroded stainless steel materials. The formation of corrosion scale is strongly related to water quality parameters. The presence of HClO results in higher ferric content inside the scales. Cl(-) and SO4(2-) ions in reclaimed water play an important role in corrosion pitting of stainless steel and promote the formation of scales.

  20. Experimental evidence for multi-element stochastic resonance in the system of membrane ion channels

    NASA Astrophysics Data System (ADS)

    Vodyanoy, Igor

    1996-03-01

    The principles of biological amplification are far from understood; it is only clear that biological amplifiers are unique in their ability to detect small signals in a noisy environment. As was shown recently, many nonlinear systems can use noise to enhance their performance, and this phenomenon, called stochastic resonance, may underline the extraordinary ability of some biological systems to detect and amplify small signals. Previous work has demonstrated stochastic resonance in complex systems of biological transducers and neural signal pathways, but the possibility that it could occur at the sub-cellular level has remained open. Here we report the observation of noise-enhanced electrical signal transfer in a simple system of voltage-dependent ion channels formed by the peptide alamethicin in a lipid bilayer footnote S.M.Bezrukov and I.Vodyanoy, Nature (London), November 1995 (in press). Channels are expressed in a stochastic manner as "current bursts" rising from the background, and their formation is highly voltage-sensitive. An average alamethicin- induced conductance increases e-fold every 4 or 5 mV, depending on bilayer lipid composition. Alamethicin channel transitions between nonconducting and conducting aggregates can be described by a quasi-bistable energy diagram, where the probability distribution along the reaction coordinate is sensitive to the transmembrane voltage mostly at the level of the transition between two main energy wells. To study the interaction between external noise and signal transfer, we measure amplitude of output signal and the signal-to-noise ratio at the system output as a function of external noise intensity. We show that a hundred-fold increase in signal transduction induced by external noise is accompanied by a growth in the output signal-to-noise ratio. Recent theory and numerical simulation dealing with a parallel combination of noniteracting stochastic resonant elements may provide an explanation of the present results

  1. Amendment of biochar reduces the release of toxic elements under dynamic redox conditions in a contaminated floodplain soil.

    PubMed

    Rinklebe, Jörg; Shaheen, Sabry M; Frohne, Tina

    2016-01-01

    Biochar (BC) can be used to remediate soils contaminated with potential toxic elements (PTEs). However, the efficiency of BC to immobilize PTEs in highly contaminated floodplain soils under dynamic redox conditions has not been studied up to date. Thus, we have (i) quantified the impact of pre-definite redox conditions on the release dynamics of dissolved aluminum (Al), arsenic (As), cadmium (Cd), copper (Cu), nickel (Ni), and zinc (Zn) in a highly contaminated soil (CS) (non-treated) and in the same soil treated with 10 g kg(-1) biochar based material (CS+BC), and (ii) assessed the efficacy of the material to reduce the concentrations of PTEs in soil solution under dynamic redox conditions using an automated biogeochemical microcosm apparatus. The impact of redox potential (EH), pH, dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), iron (Fe), manganese (Mn), and sulfate (SO4(2-)) on dynamics of PTEs was also determined. The EH was lowered to +68 mV and afterwards increased stepwise to +535 mV. Significant negative correlation between EH and pH in CS and CS+BC was detected. The systematic increase of EH along with decrease of pH favors the mobilization of PTEs in CS and CS+BC. The material addition seems to have little effect on redox processes because pattern of EH/pH and release dynamics of PTEs was basically similar in CS and CS+BC. However, concentrations of dissolved PTEs were considerably lower in CS+BC than in CS which demonstrates that BC is able to decrease concentrations of dissolved PTEs even under dynamic redox conditions.

  2. Studies on heme release from normal and metal ion reconstituted hemoglobin mediated through ionic surfactant.

    PubMed

    Venkatesh, Balan; Venkatesh, S; Jayadevan, S; Rifkind, Joseph M; Manoharan, P T

    2005-01-01

    The interaction of metal-substituted hemoglobin (MHb), where M = Ni and Cu (T-state with no O2 and CO binding capability) and Fe (R-state when CO is bound), with cationic cityl trimethyl ammonium bromide (CTAB) and anionic (sodium dodecyl sulfate-SDS) surfactants has been studied using spectroscopic techniques-UV-visible, electron paramagnetic resonance (EPR), and Fourier transform-Raman-with additional supportive evidence coming from conductivity measurements. We observed the loss of 5-coordination in all three hemoglobins below the critical micelle concentration (CMC) of surfactant, with noticeable differences, suggesting differing mechanisms involved in this process. In addition, above the CMC, Ni- and Cu-hemes were found to leave their proteins more easily than Fe-heme, presumably due to weaker or no bond with the proximal histidine in the former. The released heme is stabilized by micellar media through a hydrophobic interaction process. Of the two surfactants, CTAB seems to be capable of releasing the heme better than SDS and it is attributed to the greater hydrophobicity of CTAB though the charge of the surfactant plays an important role.

  3. Microanalyses of O isotopes and elemental ratios of reef building coral (Montastrea annularis) by ion microprobe

    NASA Astrophysics Data System (ADS)

    Gabitov, R. I.; Carricart Ganivet, J. P.; Prieto, R. I.

    2012-12-01

    Our understanding of climate change and oceanographic variability through time is largely derived from knowledge of oxygen isotopes (δ18O) and elemental ratios (X/Ca) signatures in coral reefs. However, the existence of inconsistencies in isotopic composition between different coral specimens suggests that factors other than temperature and seawater composition affect isotopic and chemical records. We conducted in situ Secondary Ion Mass Spectrometry (SIMS) analyses on the reef building coral (Montastraea annularis) from Veracuz Reef in the southern Gulf of Mexico. Coral specimen was sliced in perpendicular and parallel directions of its growth. Therefore, one of the sections exposed simultaneously grown skeletal material; another section represents a time series of continuously extended skeleton. The complex microstructure of the coral yields a few morphologically different zones (architectural elements). There are theca-wall (Th), septa (S), costa (C), exothecal (ExD) and endothecal dissepiments (EnD). Dissepiments formation in Montastraea annularis is linked to moon cycles and there are 12 or 13 ExD formed per year; meanwhile, there are 24 or 26 EnD per year (Dávalos-Dehullu et al. 2008). SIMS analyses were performed on Th, S, C, ExD, and EnD at lateral spatial resolution of ~20 μm. SIMS spot profiles with 100 and 500 μm steps were conducted on Th wall in the direction of coral growth. SIMS analyses demontrate that δ18O in Th, S, C, and ExD that grown at the same time are similar to each other within 1 sigma error. However, δ18O in EnD is isotopically heavier by 1 ‰ than those of simultaneously grown T,S, and ExD. The reverse dependence of δ18O on growth rate of corals and inorganically precipitated aragonite was reported by previous works and potentially could explain the δ18O enrichment in EnD, which grow by 35% slower than ExD (McConnaughey 1989; Dávalos-Dehullu et al. 2008; Gabitov 2012). SIMS spot profiles in the coral growth direction yielded

  4. PreCisIon: PREdiction of CIS-regulatory elements improved by gene’s positION

    PubMed Central

    Elati, Mohamed; Nicolle, Rémy; Junier, Ivan; Fernández, David; Fekih, Rim; Font, Julio; Képès, François

    2013-01-01

    Conventional approaches to predict transcriptional regulatory interactions usually rely on the definition of a shared motif sequence on the target genes of a transcription factor (TF). These efforts have been frustrated by the limited availability and accuracy of TF binding site motifs, usually represented as position-specific scoring matrices, which may match large numbers of sites and produce an unreliable list of target genes. To improve the prediction of binding sites, we propose to additionally use the unrelated knowledge of the genome layout. Indeed, it has been shown that co-regulated genes tend to be either neighbors or periodically spaced along the whole chromosome. This study demonstrates that respective gene positioning carries significant information. This novel type of information is combined with traditional sequence information by a machine learning algorithm called PreCisIon. To optimize this combination, PreCisIon builds a strong gene target classifier by adaptively combining weak classifiers based on either local binding sequence or global gene position. This strategy generically paves the way to the optimized incorporation of any future advances in gene target prediction based on local sequence, genome layout or on novel criteria. With the current state of the art, PreCisIon consistently improves methods based on sequence information only. This is shown by implementing a cross-validation analysis of the 20 major TFs from two phylogenetically remote model organisms. For Bacillus subtilis and Escherichia coli, respectively, PreCisIon achieves on average an area under the receiver operating characteristic curve of 70 and 60%, a sensitivity of 80 and 70% and a specificity of 60 and 56%. The newly predicted gene targets are demonstrated to be functionally consistent with previously known targets, as assessed by analysis of Gene Ontology enrichment or of the relevant literature and databases. PMID:23241390

  5. [Study on the release of copper ion and corrosion for intrauterine contraceptive device with two kinds of Cu-containing stent].

    PubMed

    Zou, Fengping; Huang, Shuze; Ji, Rong; Ding, Biao; Yao, Tianping

    2014-05-01

    Two kinds of Cu-containing intrauterine contraceptive device (Cu-IUD) has been evaluated through the study on the release of copper ion and corrosion of copper surface in artificially formulated fluid. The result showed that the copper ions were released profusely from the stainless steel stents Cu-IUD in the first week of soak (25-12 microg/d), and then it became slowly and steady. The release of the copper ions from the titanium nickel shape memory alloy stents Cu-IUD were always slowly and steady in two months (0.5-5 microg/d). It obviously shows that the corrosion on copper surface of stainless steel stents Cu-IUD were more serious than titanium nickel shape memory alloy stents Cu-IUD by using 200 times microscope testing before and after soaking in formulated fluid.

  6. Novel model of negative secondary ion formation and its use to refine the electronegativity of almost fifty elements.

    PubMed

    Wittmaack, Klaus

    2014-06-17

    This study aimed to examine the recently proposed idea that the ionic contribution to atomic bonds is essential in determining the charge state of sputtered atoms. Use was made of negative secondary ion yields reported by Wilson for a large number of elements implanted in silicon and then sputter profiled by Cs bombardment. The derived normalized ion yields (or fractions) P vary by 6 orders of magnitude, but the expected exponential dependence on the electron affinity EA is evident only vaguely. Remarkably, a correlation of similar quality is observed if the data are presented as a function of the ionization potential IP. With IP being the dominant (if not sole) contributor to the electronegativity χ, one is led to assume that P depends on the sum χ + EA. About 72% of the "nonsaturated" ion yields are in accordance with a dependence of the form P ∝ exp[(χ + EA)/ε], with ε ≅ 0.2 eV, provided the appropriate value of χ is selected from the electronegativity tables of Pauling (read in eV), Mulliken or Allen. However, each of the three sources contributes only about one-third to the favorable electronegativity data. This unsatisfactory situation initiated the idea to derive the "true" electronegativity χSIMS from the measured ion yields P(χ + EA), verified for 48 elements. Significant negative deviations of χSIMS from a smooth increase with increasing atomic number are evident for elements with special outer-shell electron configurations such as (n-1)d(g-1)ns(1) or (n-1)d(10)ns(2)np(1). The results strongly support the new model of secondary ion formation and provide means for refining electronegativity data.

  7. Single element of the matrix source of negative hydrogen ions: Measurements of the extracted currents combined with diagnostics

    SciTech Connect

    Yordanov, D. Lishev, St.; Shivarova, A.

    2016-02-15

    Combining measurements of the extracted currents with probe and laser-photodetachment diagnostics, the study is an extension of recent tests of factors and gas-discharge conditions stimulating the extraction of volume produced negative ions. The experiment is in a single element of a rf source with the design of a matrix of small-radius inductively driven discharges. The results are for the electron and negative-ion densities, for the plasma potential and for the electronegativity in the vicinity of the plasma electrode as well as for the currents of the extracted negative ions and electrons. The plasma-electrode bias and the rf power have been varied. Necessity of a high bias to the plasma electrode and stable linear increase of the extracted currents with the rf power are the main conclusions.

  8. Ion pickup observed at comet 67P with the Rosetta Plasma Consortium (RPC) particle sensors: similarities with previous observations and AMPTE releases, and effects of increasing activity

    NASA Astrophysics Data System (ADS)

    Coates, A. J.; Burch, J. L.; Goldstein, R.; Nilsson, H.; Stenberg Wieser, G.; Behar, E.; the RPC Team

    2015-09-01

    Rosetta's unique trajectory is allowing exciting measurements of the development of cometary activity between ˜3.6 and 1.2 AU for the first time. For a few months following Rosetta's arrival at comet 67P in August 2014, data from the Rosetta Plasma Consortium (RPC) particle instruments (the Ion and Electron Spectrometer (IES) and the Ion Composition Analyser (ICA)), have shown that the low activity cometary environment was initially dominated by the solar wind. This was expected in the early stages of the mission. In addition to the solar wind and related He+ populations, a low energy pickup ion population is seen intermittently in the early phase of the mission near the comet. The population is very time dependent, but at times reaches higher energy approaching the solar wind energy. During these intervals, ICA data indicate that the composition is mainly water group ions. The rising energy signatures of these ions observed at times indicate that they are in the early phases of the pickup process, initially accelerated by the electric field (‘early phase pickup’). Here, we compare these exciting pickup ion measurements with Giotto measurements at the relatively weak (compared to Halley) comet Grigg-Skjellerup, where early phase pickup was seen including non-gyrotropic cometary ions, and with the AMPTE lithium and barium releases. Our results reveal some striking similarities with the AMPTE releases, particularly the rising energy signature related to early pickup, and a momentum balance between the pickup ions and the deflected solar wind. There is also evidence for momentum transfer between the pickup ions and the solar wind, with less velocity change seen in the solar wind alpha particles compared to the protons; this was also observed in an AMPTE lithium release. We discuss the effects of increasing activity observed between 3.6 to 1.8 AU, including the increasing dominance and energisation of pickup ions, increasing ionospheric effects and the decreasing

  9. Origin of trace elements and inorganic ions in PM 10 aerosols to the South of Mexico City

    NASA Astrophysics Data System (ADS)

    Báez, P. A.; García, M. R.; Torres, B. M. del C.; Padilla, H. G.; Belmont, R. D.; Amador, O. M.; Villalobos-Pietrini, R.

    2007-07-01

    Measurements of trace metals and inorganic ions were carried out on PM 10 aerosols. Sampling was made in the southern section of downtown Mexico City. Samples were collected with an Andersen PM 10 high volume sampler, on glass fiber filters. The ions SO 42-, NO 3-, Cl -, and NH 4+ were analyzed by ion chromatography, Na +, K +, Ca 2+ and Mg 2+ by flame atomic absorption spectroscopy and the trace metals using an atomic absorption spectrometer with a graphite furnace attachment. The results indicated that SO 42- was the most abundant ion, and with respect to trace metals, Pb had the highest concentration in spite of the fact that lead tetraethyl content in gasoline is prohibited by Mexican Federal Law. Pearson's correlation, applied to all data, showed a high correlation among SO 42-, NO 3- and NH 4+, indicating a common anthropogenic origin. In addition the correlation found between Na + and K + indicated a crustal origin. No correlation among the trace metals was found. The scatter plots showed a high neutralization of SO 42- and NO 3- by NH 4+, (NH 4) 2SO 4 and NH 4NO 3 were the major species formed. Enrichment factors were calculated using K as a reference and the results reflected the possible origins of the elements: crustal or anthropogenic. In order to gain a better insight into the origin of trace metals and major inorganic ions, a Principal Component Analysis was applied to the results for 10 elements and 4 ions, for the years 2003 and 2004. Sources of anthropogenic species, such as industries and vehicles are discussed.

  10. Metal-ion release from titanium and TiN coated implants in rat bone*

    NASA Astrophysics Data System (ADS)

    Ferrari, F.; Miotello, A.; Pavloski, L.; Galvanetto, E.; Moschini, G.; Galassini, S.; Passi, P.; Bogdanović, S.; Fazinić, S.; Jaksić, M.; Valković, V.

    1993-06-01

    Titanium is a good material for dental and orthopaedic implants, but many authors reported that it releases ions into the surrounding tissues and into the serum. Titanium nitride has good mechanical properties and chemical inertless and may be employed as an implant coating material. In this experiment, pure titanium and SiO 2 coated with TiN implants were inserted in the tibia of rats. After thirty days, the bones were taken and examined by a proton microprobe. TiN-coated implants showed a lower ion release into the bone compared with pure titanium. This suggests that TiN may be a good coating for endosseous implants.

  11. Silver release and antimicrobial properties of PMMA films doped with silver ions, nano-particles and complexes.

    PubMed

    Lyutakov, O; Goncharova, I; Rimpelova, S; Kolarova, K; Svanda, J; Svorcik, V

    2015-04-01

    Materials prepared on the base of bioactive silver compounds have become more and more popular due to low microbial resistance to silver. In the present work, the efficiency of polymethylmethacrylate (PMMA) thin films doped with silver ions, nanoparticles and silver-imidazole polymer complex was studied by a combination of AAS, XPS and AFM techniques. The biological activities of the proposed materials were discussed in view of the rate of silver releasing from the polymer matrix. Concentrations of Ag active form were estimated by its ability to interact with l-cysteine using electronic circular dichroism spectroscopy. Rates of the released silver were compared with the biological activity in dependence on the form of embedded silver. Antimicrobial properties of doped polymer films were studied using two bacterial strains: Staphylococcus epidermidis and Escherichia coli. It was found that PMMA films doped with Ag(+) had greater activity than those doped with nanoparticles and silver-imidazole polymeric complexes. However, the antimicrobial efficiency of Ag(+) doped films was only short-term. Contrary, the antimicrobial activity of silver-imidazole/PMMA films increased in time of sample soaking.

  12. The salt and lipid composition of model cheeses modifies in-mouth flavour release and perception related to the free sodium ion content.

    PubMed

    Boisard, Lauriane; Andriot, Isabelle; Martin, Christophe; Septier, Chantal; Boissard, Vanessa; Salles, Christian; Guichard, Elisabeth

    2014-02-15

    Reducing salt and lipid levels in foodstuffs without any effect on acceptability is a major challenge, particularly because of their interactions with other ingredients. This study used a multimodal approach to understand the effects of changes to the composition of model cheeses (20/28, 24/24, 28/20 lipid/protein ratios, 0% and 1% added NaCl) on sodium ion mobility ((23)Na NMR), in-mouth sodium release and flavour perception. An increase in the salt content decreased cheese firmness and perceived hardness, and increased sodium ion mobility, in vivo sodium release and both saltiness and aroma perception. With the same amount of salt, a lower lipid/protein ratio increased the firmness of the cheeses, perceived hardness, and decreased sodium ion mobility, in vivo sodium release, saltiness and aroma perception. These findings suggest on one hand that it could be possible to increase saltiness perception by varying cheese composition, thus inducing differences in sodium ion mobility and in free sodium ion concentration, leading to differences in in-mouth sodium release and saltiness perception, and on the other hand that the reformulation of foods in line with health guidelines needs to take account of both salt content and the lipid/protein ratio.

  13. Investigation on the ion pair amphiphiles and their in vitro release of amantadine drug based on PLGA-PEG-PLGA gel

    NASA Astrophysics Data System (ADS)

    Yang, Xiaoxia; Ji, Xiaoqing; Shi, Chunhuan; Liu, Jing; Wang, Haiyang; Luan, Yuxia

    2014-12-01

    The amantadine drug and oleic acid surfactant are used to form amantadine-based ion pair amphiphiles based on proton transfer reaction between the drug and the surfactant molecules. The ion pair amphiphiles are characterized by 1H-nuclear magnetic resonance, Fourier transform infrared spectroscopy, and X-ray diffraction. Self-assembly properties of amantadine-based ion pair amphiphiles are studied by surface tension determination, transmission electron microscopy, zeta potential, and dynamic light scattering. The aggregation behavior studies indicate that the as-prepared ion pair amphiphiles can self-assemble into vesicles with the size of 200-300 nm in aqueous solution. The drug release results show that the amantadine release rate could be well controlled by incorporating the amantadine-based ion pair vesicles in poly (lactic-co-glycolic acid)-poly (ethylene glycol)-poly (lactic-co-glycolic acid) (PLGA-PEG-PLGA) copolymer hydrogel. The drug release from the AT-OA vesicle-loaded PLGA-PEG-PLGA hydrogel is significantly inhibited in comparison with the AT-loaded PLGA-PEG-PLGA hydrogel. The present work thus demonstrates that the vesicle-loaded hydrogel is a good candidate for the drug delivery system with long-term controlled drug release behavior.

  14. Guidelines for Designing Surface Ion Traps Using the Boundary Element Method

    PubMed Central

    Hong, Seokjun; Lee, Minjae; Cheon, Hongjin; Kim, Taehyun; Cho, Dong-il “Dan”

    2016-01-01

    Ion traps can provide both physical implementation of quantum information processing and direct observation of quantum systems. Recently, surface ion traps have been developed using microfabrication technologies and are considered to be a promising platform for scalable quantum devices. This paper presents detailed guidelines for designing the electrodes of surface ion traps. First, we define and explain the key specifications including trap depth, q-parameter, secular frequency, and ion height. Then, we present a numerical-simulation-based design procedure, which involves determining the basic assumptions, determining the shape and size of the chip, designing the dimensions of the radio frequency (RF) electrode, and analyzing the direct current (DC) control voltages. As an example of this design procedure, we present a case study with tutorial-like explanations. The proposed design procedure can provide a practical guideline for designing the electrodes of surface ion traps. PMID:27136559

  15. The Effect of Annealing at 1500 C on Migration and Release of Ion Implanted Silver in CVD Silicon Carbide

    SciTech Connect

    HJ MacLean; RG Ballinger; LE Kolaya; SA Simonson; N Lewis; M Hanson

    2004-10-07

    The transport of silver in CVD {beta}-SiC has been studied using ion implantation. Silver ions were implanted in {beta}-SiC using the ATLAS accelerator facility at the Argonne National Laboratory. Ion beams with energies of 93 and 161 MeV were used to achieve deposition with peak concentrations at depths of approximately 9 and 13 {micro}m, respectively. As-implanted samples were then annealed at 1500 C for 210 or 480 hours. XPS, SEM, TEM, STEM, and optical methods were used to analyze the material before and after annealing. Silver concentration profiles were determined using XPS before and after annealing. STEM and SEM equipped with quantitative chemical analysis capability were used to more fully characterize the location and morphology of the silver before and after annealing. The results show that, within the uncertainty of measurement techniques, there is no silver migration, via either inter- or intragrannular paths, for the times and temperature studied. Additionally, the silver was observed to phase separate within the SiC after annealing. The irradiation damage from the implantation process resulted in a three-layer morphology in the as-implanted condition: (1) a layer of unaltered SiC, followed by (2) a layer of crystallized SiC, followed by (3) an amorphized layer which contained essentially all of the implanted silver. After annealing the layer structure changed. Layer 1 was unaltered. The grains in layer 2 recrystallized to form an epitaxial (columnar) layer. Layer 3 recrystallized to form a fine grain equiaxed layer. The results of this work do not support the long held assumption that silver release from CVD SiC, used for gas-reactor coated particle fuel, is dominated by grain boundary diffusion.

  16. Stanford-USGS shrimp-RG ion microprobe: A new approach to determining the distribution of trace elements in coal

    USGS Publications Warehouse

    Kolker, A.; Wooden, J.L.; Persing, H.M.; Zielinski, R.A.

    2000-01-01

    The distribution of Cr and other trace metals of environmental interest in a range of widely used U.S. coals was investigated using the Stanford-USGS SHRIMP-RG ion microprobe . Using the oxygen ion source, concentrations of Cr (11 to 176 ppm), V (23 to 248 ppm), Mn (2 to 149 ppm), Ni (2 to 30 ppm), and 13 other elements were determined in illite/smectite, a group of clay minerals commonly present in coal. The results confirm previous indirect or semi-quantitative determinations indicating illite/smectite to be an important host of these metals. Calibration was achieved using doped aluminosilicate-glass synthetic standards and glasses prepared from USGS rock standards. Grains for analysis were identified optically, and confirmed by 1) precursory electron microprobe analysis and wavelength-dispersive compositional mapping, and 2) SHRIMP-RG major element data obtained concurrently with trace element results. Follow-up investigations will focus on the distribution of As and other elements that are more effectively ionized with the cesium primary beam currently being tested.

  17. Multi-Element Preconcentration/Separation of Some Metal Ions in Environmental Samples by Using Co-precipitation.

    PubMed

    Soylak, Mustafa; Aydin, Ayse; Kizil, Nebiye

    2016-01-01

    A preconcentration/separation system for cadmium(II), nickel(II), copper(II), lead(II), iron(II), cobalt(II), and manganese(II) ions has been established prior to their atomic absorption spectrometric determinations. The procedure is based on the co-precipitation of these ions by the aid of a praseodymium hydroxide (Pr(OH)3) precipitate. The precipitate was dissolved in 0.5 mL of concentrated HNO3, and made up to 10.0 mL with water. The analytes were determined by a flame atomic absorption spectrometer. The effects of analytical parameters including pH, amounts of praseodymium as carrier element, sample volume, etc. on the recoveries of heavy metals were investigated. The effects of matrix ions were also examined. The limits of detection for analyte ions were found in the range between 0.7-5.2 μg/L. The validation of this present procedure was verified by the analysis of certified reference materials, TMDA-54.4 (fortified water) and NIST 1570a (spinach leaves). The proposed co-precipitation procedure was applied for the determination of cadmium(II), nickel(II), copper(II), lead(II), iron(II), cobalt(II), and manganese(II) ions in various environmental water samples.

  18. Direct Trace Element Analysis of Liquid Blood Samples by In-Air Ion Beam Analytical Techniques (PIXE-PIGE).

    PubMed

    Huszank, Robert; Csedreki, László; Török, Zsófia

    2017-02-07

    There are various liquid materials whose elemental composition is of interest in various fields of science and technology. In many cases, sample preparation or the extraction can be complicated, or it would destroy the original environment before the analysis (for example, in the case of biological samples). However, multielement direct analysis of liquid samples can be realized by an external PIXE-PIGE measurement system. Particle-induced X-ray and gamma-ray emission spectroscopy (PIXE, PIGE) techniques were applied in external (in-air) microbeam configuration for the trace and main element determination of liquid samples. The direct analysis of standard solutions of several metal salts and human blood samples (whole blood, blood serum, blood plasma, and formed elements) was realized. From the blood samples, Na, P, S, Cl, K, Ca, Fe, Cu, Zn, and Br elemental concentrations were determined. The focused and scanned ion beam creates an opportunity to analyze very small volume samples (∼10 μL). As the sample matrix consists of light elements, the analysis is possible at ppm level. Using this external beam setup, it was found that it is possible to determine elemental composition of small-volume liquid samples routinely, while the liquid samples do not require any preparation processes, and thus, they can be analyzed directly. In the case of lower concentrations, the method is also suitable for the analysis (down to even ∼1 ppm level) but with less accuracy and longer measurement times.

  19. Polyglycerol-Based Copper Chelators for the Transport and Release of Copper Ions in Biological Environments.

    PubMed

    Albrecht, Ralf; Fehse, Susanne; Pant, Kritee; Nowag, Sabrina; Stephan, Holger; Haag, Rainer; Tzschucke, Carl Christoph

    2016-03-01

    Here, the synthesis and characterization of three improved nanosystems is presented based on amino functionalized hyperbranched polyglycerol (hPG; M(w) = 16.8 kDa) as potential copper(II) chelators. The ligands, N-methyl-N-picolylglycine amide, 2,6-pyridine dicarboxylic acid monoamide, and cyclam tetraacetic acid (TETA) monoamide, are covalently attached to the polymer with amide bonds. In this paper, the Cu(II) loading capacity, the stability of the Cu(II)-loaded carriers at different pHs, with competing ligands and in human serum, as well as the transport of Cu(II) in biological systems are investigated. For the first time, a different cytotoxicity of functionalized polymer nanoparticles with and without Cu(II) is observed. The cyclam-based carrier combines the highest loading capacity (29 Cu ions/nanoparticle), best stability with respect to pH and EDTA (45% remaining Cu after 24 h), lowest cytotoxicity (IC50 > 100 × 10(-6) M (unloaded), 1500 × 10(-6) M Cu(II); Cu:carrier 29:1), and the highest stability in human serum.

  20. Alcohol dysregulates corticotropin-releasing-hormone (CRH) promoter activity by interfering with the negative glucocorticoid response element (nGRE).

    PubMed

    Przybycien-Szymanska, Magdalena M; Mott, Natasha N; Pak, Toni R

    2011-01-01

    EtOH exposure in male rats increases corticotropin-releasing hormone (CRH) mRNA in the paraventricular nucleus of the hypothalamus (PVN), a brain region responsible for coordinating stress and anxiety responses. In this study we identified the molecular mechanisms involved in mediating these effects by examining the direct effects of EtOH on CRH promoter activity in a neuronal cell line derived from the PVN (IVB). In addition, we investigated the potential interactions of EtOH and glucocorticoids on the CRH promoter by concomitantly treating cells with EtOH and the glucocorticoid receptor (GR) antagonist RU486, and by sequentially deleting GR binding sites within glucocorticoid response element (GRE) on the CRH promoter. Cells were transiently transfected with a firefly luciferase reporter construct containing 2.5 kb of the rat wild type (WT) or mutated CRH promoter. Our results showed that EtOH treatment induced a biphasic response in CRH promoter activity. EtOH exposure for 0.5 h significantly decreased promoter activity compared to vehicle treated controls, whereas promoter activity was significantly increased after 2.0 h of EtOH exposure. Treatment with RU486, or deletion of the GR binding sites 1 and 2 within the GRE, abolished the EtOH-induced increase in the promoter activity, however did not affect EtOH-induced decrease in CRH promoter activity at an earlier time point. Overall, our data suggest that alcohol exposure directly regulates CRH promoter activity by interfering with the normal feedback mechanisms of glucocorticoids mediated by GR signaling at the GRE site of the CRH promoter.

  1. Development of a high intensity 48Ca ion beam for the heavy element program

    SciTech Connect

    Wutte, Daniela; Leitner, Mattheus; Lyneis, Claude

    2002-02-02

    A high intensity {sup 48}Ca ion beam has been developed at the 88 Inch Cyclotron for the synthesis of {sup 283}112 using the reaction {sup 238}U({sup 48}Ca, 3n). An ion beam intensity of {approx} 700 pnA was delivered on target, resulting in a total dose of 2 x 10{sup 18} ions over a six day period. Since {sup 48}Ca is a very expensive and rare isotope minimal consumption is essential. Therefore a new oven [1] and special tantalum liner [2] have been developed for the AECR-U ion source during the last year to improve the metal ion beam efficiency. Both the LBL ECR and the AECR-U ion sources are built with radial access. Six radial slots between the sextupole magnet bars provide additional pumping and easy access to the plasma chamber for ovens and feedthroughs. Two types of radial ovens have been used at LBNL in the past, operating at temperatures up to 2100 C.

  2. Observation of lithium pick-up ions in the 5- to 20-keV energy range following the AMPTE solar wind releases

    SciTech Connect

    Moebius, E.; Hovestadt, D.; Klecker, B.; Scholer, M.; Gloeckler, G.; Ipavich, F.M.; Luehr, H.

    1986-02-01

    Newly created 5- to 20-keV lithium ions were observed for limited time periods following the first Active Magnetospheric Particle Tracer Explorers (AMPTE) lithium release in the solar wind on September 11, 1984. The detection of these so-called ''pick-up'' ions by the time-of-flight spectrometer SULEICA (suprathermal energy ionic charge analyzer) on the AMPTE/IRM satellite depends critically on the orientation of the interplanetary magnetic field with respect to the directions of the solar wind and the spin axis of the IRM spacecraft, which was favorable only during the short time when these ions were seen. Our observations are compatible with a shell-like expansion of the Li cloud with velocities of about 2.5 km/s. The signatures by which the artificial pick-up ions are identified can also be used to detect and investigate natural pick-up ions.

  3. Continuous ice core melter system with discrete sampling for major ion, trace element and stable isotope analyses.

    PubMed

    Osterberg, Erich C; Handley, Michael J; Sneed, Sharon B; Mayewski, Paul A; Kreutz, Karl J

    2006-05-15

    We present a novel ice/firn core melter system that uses fraction collectors to collect discrete, high-resolution (<1 cm/sample possible), continuous, coregistered meltwater samples for analysis of eight major ions by ion chromatography (IC), >32 trace elements by inductively coupled plasma sectorfield mass spectrometry (ICP-SMS), and stable oxygen and hydrogen isotopes by isotope ratio mass spectrometry (IRMS). The new continuous melting with discrete sampling (CMDS) system preserves an archive of each sample, reduces the problem of incomplete particle dissolution in ICP-SMS samples, and provides more precise trace element data than previous ice melter models by using longer ICP-SMS scan times and washing the instrument between samples. CMDS detection limits are similar to or lower than those published for ice melter systems coupled directly to analytical instruments and are suitable for analyses of polar and mid-low-latitude ice cores. Analysis of total calcium and sulfur by ICP-SMS and calcium ion, sulfate, and methanesulfonate by IC from the Mt. Logan Prospector-Russell Col ice core confirms data accuracy and coregistration of the split fractions from each sample. The reproducibility of all data acquired by the CMDS system is confirmed by replicate analyses of parallel sections of the GISP2 D ice core.

  4. Mapping of light elements with the ANSTO high energy heavy ion microprobe

    NASA Astrophysics Data System (ADS)

    Siegele, Rainer; Cohen, David D.

    2000-03-01

    7.62 MeV He was used to study the distribution of a wide range of elements in mineral sands. At this energy both He induced X-ray emission and a high energy resonance in oxygen can be applied simultaneously. The two techniques were used to study the distribution of elements ranging from sulfur to zirconium as well as oxygen.

  5. Corrosion, ion release and Mott-Schottky probe of chromium oxide coatings in saline solution with potential for orthopaedic implant applications

    NASA Astrophysics Data System (ADS)

    Ogwu, A. A.; Oje, A. M.; Kavanagh, J.

    2016-04-01

    We report our investigation on chromium oxide thin film coatings that show a negligible ion release during electrochemical corrosion testing in saline solution. The chemical constituents of the films prepared by reactive magnetron sputtering were identified to be predominantly Cr2O3 based on Raman spectroscopy anti-symmetric stretching vibration modes for CrIII-O and other peaks and an FTIR spectroscopy E u vibrational mode at 409 cm-1. X-ray photoelectron spectroscopy, multiplet fitting for 2P 3/2 and 2P 1/2 states also confirmed the predominantly Cr2O3 stoichiometry in the films. The prepared chromium oxide coatings showed superior pitting corrosion resistance compared to the native chromium oxide films on bare uncoated stainless steel when tested under open circuit potential, potentiodynamic polarisation and cyclic voltammetry in saline solution. The chromium ion released into solution during the corrosion testing of stainless steel substrates coated with chromium oxide coatings was found to be negligibly small based on atomic absorption spectroscopy measurements. Our Mott-Schottky analysis investigation showed that the negligibly small ion release from the chromium oxide coated steel substrates is most likely due to a much lower defect density on the surface of the deposited coatings compared to the native oxide layer on the uncoated steel substrates. This opens up the opportunity for using chromium oxide surface coatings in hip, knee and other orthopaedic implants where possible metal ion release in vivo still poses a great challenge.

  6. Structure-dependent deuterium release from ion implanted beryllium: Comparison between Be(1 1 2¯ 0) and Be(poly)

    NASA Astrophysics Data System (ADS)

    Oberkofler, M.; Reinelt, M.; Lindig, S.; Linsmeier, Ch.

    2009-02-01

    The temperature-driven release of deuterium implanted as keV ions into metallic beryllium is measured by temperature-programmed desorption (TPD). TPD spectra from single and polycrystalline Be implanted with 1 keV ions are compared. The high-temperature desorption stage (T > 700 K) is attributed to the release of deuterium trapped at several types of energetically different ion-induced defects. A release peak around 850 K is recorded in the single crystal, while in the polycrystal all deuterium desorbs below this temperature. An increase in the maximum release temperature is observed after implantation of the polycrystal with higher ion energies (2 and 3 keV). We propose an interpretation of the experimental results based on two types of traps, with depth distributions adapted to the implantation energy. Preliminary TMAP7 calculations qualitatively reproduce the shifts in the maximum desorption temperature, observed in the polycrystal at different implantation energies. The difference between the single and the polycrystal is explained by a higher density of surviving defects in the single crystal. Diffusion of mobile defects to grain boundaries and subsequent annihilation is proposed as the dominant mechanism for differences in deuterium desorption from Be(1 1 2 bar 0) and Be(poly).

  7. Evaluation of Nickel and Chromium Ion Release During Fixed Orthodontic Treatment Using Inductively Coupled Plasma-Mass Spectrometer: An In Vivo Study

    PubMed Central

    Nayak, Rabindra S; Khanna, Bharti; Pasha, Azam; Vinay, K; Narayan, Anjali; Chaitra, K

    2015-01-01

    Background: Fixed orthodontic appliances with the use of stainless steel brackets and archwires made of nitinol have a corrosive potential in the oral environment. Nickel and chromium ions released from these appliances act as allergens apart from being cytotoxic, mutagenic and carcinogenic in smaller quantities in the range of nanograms. This study was done to evaluate the release of nickel and chromium ions from orthodontic appliances in the oral cavity using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Materials and Methods: Saliva samples from 30 orthodontic patients undergoing treatment with 0.022″ MBT mechanotherapy were collected prior to commencement of treatment, after initial aligning wires and after 10-12 months of treatment. Salivary nickel and chromium ion concentration was measured in parts per billion (ppb) using ICP-MS. Results: Mean, standard deviation and range were computed for the concentrations of ions obtained. Results analyzed using ANOVA indicated a statistically significant increase of 10.35 ppb in nickel ion concentration and 33.53 ppb in chromium ion concentration after initial alignment. The ionic concentration at the end of 10-12 months of treatment showed a statistically significant increase in of 17.92 ppb for chromium and a statistically insignificant decrease in nickel ion concentration by 1.58 ppb. Pearson’s correlation coefficient showed a positive correlation for an increase in nickel concentration after aligning, but not at the end of 10-12 months. A positive correlation was seen for an increase in chromium ion concentration at both time intervals. Conclusion: Nickel and chromium ion concentration in saliva even though below the recommended daily allowance should not be ignored in light of the new knowledge regarding effects of these ions at the molecular level and the allergic potential. Careful and detailed medical history of allergy is essential. Nickel free alternatives should form an essential part of an

  8. Effect of pH, fluoride and hydrofluoric acid concentration on ion release from NiTi wires with various coatings.

    PubMed

    Katic, Visnja; Curkovic, Lidija; Bosnjak, Magdalena Ujevic; Peros, Kristina; Mandic, Davor; Spalj, Stjepan

    2017-03-31

    Aim was to determine effect of pH, fluoride (F(-)) and hydrofluoric acid concentration (HF) on dynamic of nickel (Ni(2+)) and titanium (Ti(4+)) ions release. Nickel-titanium wires with untreated surface (NiTi), rhodium (RhNiTi) and nitride (NNiTi) coating were immersed once a week for five min in remineralizing agents, followed by immersion to artificial saliva. Ion release was recorded after 3, 7, 14, 21 and 28 days. Pearson correlations and linear regression were used for statistical analysis. Release of Ni(2+) from NiTi and NNiTi wires correlated highly linearly positively with HF (r=0.948 and 0.940, respectively); for RhNiTi the correlation was lower and negative (r=-0.605; p<0.05). The prediction of Ti(4+) release was significant for NiTi (r=0.797) and NNiTi (r=0.788; p<0.05) wire. Association with F(-) was lower; for pH it was not significant. HF predicts the release of ions from the NiTi wires better than the pH and F(-) of the prophylactic agents.

  9. Effect of temperature on the release and remobilization of ecotoxic elements in AMD colloidal precipitates: the example of the Libiola copper mine, Liguria, (Italy).

    PubMed

    Consani, S; Carbone, C; Salviulo, G; Zorzi, F; Dinelli, E; Botter, R; Nodari, L; Badocco, D; Lucchetti, G

    2016-07-01

    Due to their characteristics, colloidal particles are able to control the dispersion of many organic and inorganic pollutants in soils and streams. Colloidal precipitates generated by acid mine drainage (AMD) process are usually amorphous or nanocrystalline materials, and their stability plays a crucial role in controlling the fate of metals released by sulphide oxydation. This paper describes a study of elements release (Fe, Al, Mn, Cd, Co, Cr, Cu, Ni, S, Zn) due to desorption or destabilization of three different colloidal precipitates, two ochreous and a greenish-blue precipitate, sampled at the Libiola mine site (northwest Italy). The samples were heated at high temperature in order to verify this treatment as inertization process. At room temperature, the most easily extracted element was S (with released percentages from 8.39 to 29.17 %), but considerable amounts of Cu, Zn and Mn (up to 16.6, 610.6 and 595.6 mg/kg, respectively) were also observed in the leachates for greenish-blue precipitates. The highest release of elements (S > Cu, Zn, Mn, Cd > Co, Ni > Al, Fe, Cr), with minor differences depending on the mineralogical composition of the samples, was observed for heat-treated samples obtained through moderate heating and mainly formed by anhydrous phases. Samples treated at high temperature had the lowest release, with only Cu showing a significant concentration in the leachate of greenish-blue precipitates. The results showed that dissolution/desorption is limited from ochreous natural colloidal precipitates occurring at the Libiola mine site but also that high amounts of some metals can be remobilized from greenish-blue precipitates. The destabilization of all percipitates through dehydratation-dehydroxylation can further remobilize important amounts of ecotoxic elements. Heat treatment at high temperature could be a definitive, although expensive, way to fix heavy metals in the solid fraction, preventing their dispersion in the surrounding

  10. Acid-Sensing Ion Channels Activated by Evoked Released Protons Modulate Synaptic Transmission at the Mouse Calyx of Held Synapse.

    PubMed

    González-Inchauspe, Carlota; Urbano, Francisco J; Di Guilmi, Mariano N; Uchitel, Osvaldo D

    2017-03-08

    Acid-sensing ion channels (ASICs) regulate synaptic activities and play important roles in neurodegenerative diseases. We found that these channels can be activated in neurons of the medial nucleus of the trapezoid body (MNTB) of the auditory system in the CNS. A drop in extracellular pH induces transient inward ASIC currents (IASICs) in postsynaptic MNTB neurons from wild-type mice. The inhibition of IASICs by psalmotoxin-1 (PcTx1) and the absence of these currents in knock-out mice for ASIC-1a subunit (ASIC1a(-/-)) suggest that homomeric ASIC-1as are mediating these currents in MNTB neurons. Furthermore, we detect ASIC1a-dependent currents during synaptic transmission, suggesting an acidification of the synaptic cleft due to the corelease of neurotransmitter and H(+) from synaptic vesicles. These currents are capable of eliciting action potentials in the absence of glutamatergic currents. A significant characteristic of these homomeric ASIC-1as is their permeability to Ca(2+) Activation of ASIC-1a in MNTB neurons by exogenous H(+) induces an increase in intracellular Ca(2+) Furthermore, the activation of postsynaptic ASIC-1as during high-frequency stimulation (HFS) of the presynaptic nerve terminal leads to a PcTx1-sensitive increase in intracellular Ca(2+) in MNTB neurons, which is independent of glutamate receptors and is absent in neurons from ASIC1a(-/-) mice. During HFS, the lack of functional ASICs in synaptic transmission results in an enhanced short-term depression of glutamatergic EPSCs. These results strongly support the hypothesis of protons as neurotransmitters and demonstrate that presynaptic released protons modulate synaptic transmission by activating ASIC-1as at the calyx of Held-MNTB synapse.SIGNIFICANCE STATEMENT The manuscript demonstrates that postsynaptic neurons of the medial nucleus of the trapezoid body at the mouse calyx of Held synapse express functional homomeric Acid-sensing ion channel-1a (ASIC-1as) that can be activated by protons

  11. Some Rare Earth Elements Analysis by Microwave Plasma Torch Coupled with the Linear Ion Trap Mass Spectrometry

    PubMed Central

    Xiong, Xiaohong; Jiang, Tao; Qi, Wenhao; Zuo, Jun; Yang, Meiling; Fei, Qiang; Xiao, Saijin; Yu, Aimin; Zhu, Zhiqiang; Chen, Huanwen

    2015-01-01

    A sensitive mass spectrometric analysis method based on the microwave plasma technique is developed for the fast detection of trace rare earth elements (REEs) in aqueous solution. The plasma was produced from a microwave plasma torch (MPT) under atmospheric pressure and was used as ambient ion source of a linear ion trap mass spectrometer (LTQ). Water samples were directly pneumatically nebulized to flow into the plasma through the central tube of MPT. For some REEs, the generated composite ions were detected in both positive and negative ion modes and further characterized in tandem mass spectrometry. Under the optimized conditions, the limit of detection (LOD) was at the level 0.1 ng/mL using MS2 procedure in negative mode. A single REE analysis can be completed within 2~3 minutes with the relative standard deviation ranging between 2.4% and 21.2% (six repeated measurements) for the 5 experimental runs. Moreover, the recovery rates of these REEs are between the range of 97.6%–122.1%. Two real samples have also been analyzed, including well and orange juice. These experimental data demonstrated that this method is a useful tool for the field analysis of REEs in water and can be used as an alternative supplement of ICP-MS. PMID:26421013

  12. Angle-resolved intensity and energy distributions of positive and negative hydrogen ions released from tungsten surface by molecular hydrogen ion impact

    NASA Astrophysics Data System (ADS)

    Kato, S.; Tanaka, N.; Sasao, M.; Kisaki, M.; Tsumori, K.; Nishiura, M.; Matsumoto, Y.; Kenmotsu, T.; Wada, M.; Yamaoka, H.

    2015-08-01

    Hydrogen ion reflection properties have been investigated following the injection of H+, H2+ and H3+ ions onto a polycrystalline W surface. Angle- and energy-resolved intensity distributions of both scattered H+ and H- ions are measured by a magnetic momentum analyzer. We have detected atomic hydrogen ions reflected from the surface, while molecular hydrogen ions are unobserved within our detection limit. The reflected hydrogen ion energy is approximately less than one-third of the incident beam energy for H3+ ion injection and less than a half of that for H2+ ion injection. Other reflection properties are very similar to those of monoatomic H+ ion injection. Experimental results are compared to the classical trajectory simulations using the ACAT code based on the binary collision approximation.

  13. AUTOMATED ELEMENTAL COMPOSITION DETERMINATION AND CORRELATION OF PRECURSOR WITH PRODUCT IONS BASED ON ORTHOGONAL ACCELERATION, TIME-OF-FLIGHT MASS SPECTRA

    EPA Science Inventory

    For more than a decade in our laboratory, elemental compositions of ions in mass spectra havebeen routinely determined by measuring exact masses and relative isotopic abundances of ions in isotopicclusters using a GC coupled to a double focusing mass spectrometer.1 HPLC interfac...

  14. Metal ion-assisted drug-loading model for novel delivery system of cisplatin solid lipid nanoparticles with improving loading efficiency and sustained release.

    PubMed

    Yang, Caiqin; Lv, Jie; Lv, Tao; Pan, Yahui; Han, Yazhu; Zhao, Sha; Wang, Jing

    2016-05-01

    Metal ion-assisted drug loading model, in which metal ion was used to modify the microstructure of lipid layer, has been developed to improve drug loading efficiency of solid lipid nanoparticles (SLNs). The microstructure and properties of metal ion-assisted cisplatin-loading SLNs were investigated by infra-red spectroscopy, fluorescence spectroscopy and zetasizer. The reactions of hydrogenated soybean lecithin with Zn(2+), Cu(2+), Mn(2+ )and Mg(2+ )have been detected; the mechanism for higher drug encapsulation efficiency (EE) has been investigated. In metal ion introduction SLNs, the compact degree of the lipid molecules was increased due to the electrostatic interaction between metal ions and phospholipid acyl and choline polarity groups, which result in increasing of drug EE. Meanwhile, these electrostatic interactions slowed the releasing rate of encapsulated drug. The study of cytotoxic activity in vitro indicated that the cell cytotoxicity of metal ions introduction SLNs depended on both cell uptake of SLNs and drug releasing from SLNs.

  15. NUMEN Project @ LNS : Heavy ions double charge exchange reactions towards the 0νββ nuclear matrix element determination

    SciTech Connect

    Agodi, C. Calabretta, L.; Calanna, A.; Carbone, D.; Cavallaro, M.; Colonna, M.; Cuttone, G.; Finocchiaro, P.; Pandola, L.; Rifuggiato, D.; Tudisco, S.; Cappuzzello, F.; Greco, V.; Bonanno, D. L.; Bongiovanni, D. G.; Longhitano, F.; Branchina, V.; Foti, A.; Lo Presti, D.; Lanzalone, G.; and others

    2015-10-28

    In the NUMEN Project it is proposed an innovative technique to access the nuclear matrix elements entering in the expression of the life-time of the neutrinoless double beta decay, using relevant cross sections of double charge exchange reactions. A key aspect is the use of MAGNEX large acceptance magnetic spectrometer, for the detection of the ejectiles, and of the INFN Laboratori Nazionali del Sud (LNS) K800 Superconducting Cyclotron (CS), for the acceleration of the required high resolution and low emittance heavy-ion beams.

  16. Generation of Laguerre Gaussian beams using spiral phase diffractive elements fabricated on optical fiber tips using focused ion beam milling

    NASA Astrophysics Data System (ADS)

    Rodrigues Ribeiro, R. S.; Dahal, P.; Guerreiro, A.; Jorge, P. A. S.; Viegas, J.

    2016-03-01

    In this work, spiral phase lenses fabricated on the tip of single mode optical fibers are reported. This allows tailoring the fundamental guided mode, a Gaussian beam, into a Laguerre - Gaussian profile without using additional optical elements. The lenses are fabricated using Focused Ion Beam milling, enabling high resolution in the manufacturing process. The phase profiles are evaluated and validated using an implementation of the Finite Differences Time Domain. The output optical intensity profiles matching the numerical simulations are presented and analyzed. Finally, results on cell trapping and manipulation are briefly described.

  17. Behavior of transplutonium elements on ion-exchange materials in mixed aqueous-organic solutions of mineral acids

    SciTech Connect

    Guseva, L.I.; Tikhomirov, G.S.; Stepushkina, V.V.

    1987-03-01

    Systematic studies are reported on the behavior of transplutonium elements (TPE) on cation-exchange and anion-exchange materials in mixed aqueous-organic solutions of mineral acids (HClO/sub 4/, HCl, HNO/sub 3/, H/sub 2/SO/sub 4/, H/sub 3/PO/sub 4/) as affected by solution composition, nature of acid, and nature of organic solvent. With all these acids, replacing most of the water by alcohol increases the TPE uptake on the ion exchangers, and the effect occurs for the cation exchangers at lower contents of the organic component. Optimum conditions have been identified for concentrating and separating TPE from numerous elements. The most effective system consists of anion exchanger with HNO/sub 3/ and alcohol.

  18. Reduction of copper ions release by a novel ecofriendly electropolymerized nanolayer obtained from a natural compound (carvacrol).

    PubMed

    Bertuola, M; Grillo, C A; Fernández Lorenzo de Mele, M

    2016-08-05

    The release of copper ions by copper-containing devices, equipments and facilities represents a potential risk for biological systems. Different inhibitory treatments (CuIT) that use organic compounds have been proposed to reduce this environmental hazard but many of them are not in accordance with new regulations. The development of an ecofriendly CuIT based on the use of carvacrol, a natural phenolic compound present in essential oils, is reported here. The effects of carvacrol adsorption (adCarv) and its electropolymerization (polyCarv) were examined. Electropolymerization was attained after cycling the copper electrode in the 0.3-1.0V potential range. Electrochemical techniques complemented by ATR-FTIR, XPS, SEM and AFM surface analyses were used to evaluate the composition and characteristics of the layers. Results demonstrated that adCarv includes cetonic structures while polyCarv additionally contains ether bonds. AFM and SEM observations showed the presence of round nanoglobules, larger for adCarv (close to 50nm diameter). Cytotoxicity of adCarv and polyCarv layers on copper was also evaluated. The comparative analysis of both treatments revealed that polyCarv nanolayer is highly protective while the adCarv layer is weakly protective and reduction in cell viability was found. It was concluded that CuIT that leads to polyCarv nanolayer is very effective and ecofriendly.

  19. An antibiotic linked to peptides and proteins is released by electron capture dissociation fourier transform ion cyclotron resonance mass spectrometry.

    PubMed

    Fagerquist, Clifton K; Hudgins, Robert R; Emmett, Mark R; Håkansson, Kristina; Marshall, Alan G

    2003-04-01

    Desfuroylceftiofur (DFC) is a bioactive beta-lactam antibiotic metabolite that has a free thiol group. Previous experiments have shown release of DFC from plasma extracts after addition of a disulfide reducing agent, suggesting that DFC may be bound to plasma and tissue proteins through disulfide bonds. We have reacted DFC with [Arg(8)]-vasopressin (which has one disulfide bond) and bovine insulin (which has three disulfide bonds) and analyzed the reaction products by use of electron capture dissociation Fourier transform ion cyclotron resonance mass spectrometry (ECD FT-ICR MS), which has previously shown preferential cleavage of disulfide bonds. We observe cleavage of DFC from vasopressin and insulin during ECD, suggesting that DFC is indeed bound to peptides and proteins through disulfide bonds. Specifically, we observed dissociative loss of one, as well as two, DFC species during ECD of [vasopressin + 2(DFC-H) + 2H](2+) from a single electron capture event. Loss of two DFCs could arise from either consecutive or simultaneous loss, but in any case implies a gas phase disulfide exchange step. ECD of [insulin + DFC + 4H](4+) shows preferential dissociative loss of DFC. Combined with HPLC, ECD FT-ICR-MS may be an efficient screening method for detection of drug-biomolecule binding.

  20. Arachidonic acid activates release of calcium ions from reticulum via ryanodine receptor channels in C2C12 skeletal myotubes.

    PubMed

    Muslikhov, E R; Sukhanova, I F; Avdonin, P V

    2014-05-01

    Arachidonic acid causes an increase in free cytoplasmic calcium concentration ([Ca2+]i) in differentiated skeletal multinucleated myotubes C2C12 and does not induce calcium response in C2C12 myoblasts. The same reaction of myotubes to arachidonic acid is observed in Ca2+-free medium. This indicates that arachidonic acid induces release of calcium ions from intracellular stores. The blocker of ryanodine receptor channels of sarcoplasmic reticulum dantrolene (20 µM) inhibits this effect by 68.7 ± 6.3% (p < 0.001). The inhibitor of two-pore calcium channels of endolysosomal vesicles trans-NED19 (10 µM) decreases the response to arachidonic acid by 35.8 ± 5.4% (p < 0.05). The phospholipase C inhibitor U73122 (10 µM) has no effect. These data indicate the involvement of ryanodine receptor calcium channels of sarcoplasmic reticulum in [Ca2+]i elevation in skeletal myotubes caused by arachidonic acid and possible participation of two-pore calcium channels from endolysosomal vesicles in this process.

  1. Effects of alloying elements on the formation of < c >-component loops in Zr alloy Excel under heavy ion irradiation.

    SciTech Connect

    Idrees, Yasir; Francis, Elisabeth M.; Yao, Zhongwen; Korinek, Andreas; Kirk, Marquis A.; Sattari, Mohammad; Preuss, Michael; Daymond, M. R.

    2015-05-14

    We report here the microstructural changes occurring in the zirconium alloy Excel (Zr-3.5 wt% Sn-0.8Nb-0.8Mo-0.2Fe) during heavy ion irradiation. In situ irradiation experiments were conducted at reactor operating temperatures on two Zr Excel alloy microstructures with different states of alloying elements, with the states achieved by different solution heat treatments. In the first case, the alloying elements were mostly concentrated in the beta (beta) phase, whereas, in the second case, large Zr-3(Mo,Nb,Fe)(4) secondary phase precipitates (SPPs) were grown in the alpha (alpha) phase by long term aging. The heavy ion induced damage and resultant compositional changes were examined using transmission electron microscopy (TEM) in combination with scanning transmission electron microscope (STEM)-energy dispersive x-ray spectroscopy (EDS) mapping. Significant differences were seen in microstructural evolution between the two different microstructures that were irradiated under similar conditions. Nucleation and growth of < c >-component loops and their dependence on the alloying elements are a major focus of the current investigation. It was observed that the < c >-component loops nucleate readily at 100, 300, and 400 degrees C after a threshold incubation dose (TID), which varies with irradiation temperature and the state of alloying elements. It was found that the TID for the formation of < c >-component loops increases with decrease in irradiation temperature. Alloying elements that are present in the form of SPPs increase the TID compared to when they are in the beta phase solid solution. Dose and temperature dependence of loop size and density are presented. Radiation induced redistribution and clustering of alloying elements (Sn, Mo, and Fe) have been observed and related to the formation of < c >-component loops. It has been shown that at the higher temperature tests, irradiation induced dissolution of precipitates occurs whereas irradiation induced

  2. Geochemical and mineralogical controls on trace element release from the Penn Mine base-metal slag dump, California

    USGS Publications Warehouse

    Parsons, M.B.; Bird, D.K.; Einaudi, M.T.; Alpers, C.N.

    2001-01-01

    phase precipitation. Close agreement between model results and measured concentrations of Al, Ba, Cu, Fe, SiO2, and SO4 in the slag dump pore waters suggests that the dissolved concentrations of these elements are controlled by solubility equilibrium with secondary phases. Differences between predicted and measured Cd and Pb concentrations imply that field weathering rates of glass and sulfides are approximately two orders of magnitude lower than laboratory rates. Overprediction of Pb release may also reflect other attenuation processes in the natural system, such as sorption or coprecipitation. ?? 2001 Elsevier Science Ltd. All rights reserved.

  3. Trace element content and magnetic properties of commercial HOPG samples studied by ion beam microscopy and SQUID magnetometry

    SciTech Connect

    Spemann, D. Esquinazi, P. Setzer, A.; Böhlmann, W.

    2014-10-15

    In this study, the impurity concentration and magnetic response of nine highly oriented pyrolytic graphite (HOPG) samples with different grades and from different providers were determined using ion beam microscopy and SQUID magnetometry. Apart from sideface contaminations in the as-received state, bulk contamination of the samples in most cases consists of disk-shaped micron-sized particles made of Ti and V with an additional Fe contamination around the grain perimeter. The saturation magnetization typically increases with Fe concentration, however, there is no simple correlation between Fe content and magnetic moment. The saturation magnetization of one, respectively six, out of nine samples clearly exceeds the maximum contribution from pure Fe or Fe{sub 3}C. For most samples the temperature dependence of the remanence decreases linearly with T – a dependence found previously for defect-induced magnetism (DIM) in HOPG. We conclude that apart from magnetic impurities, additional contribution to the ferromagnetic magnetization exists in pristine HOPG in agreement with previous studies. A comparative study between the results of ion beam microscopy and the commonly used EDX analysis shows clearly that EDX is not a reliable method for quantitative trace elemental analysis in graphite, clarifying weaknesses and discrepancies in the element concentrations given in the recent literature.

  4. ION EXCHANGE IN FUSED SALTS. IV. DISTRIBUTION OF SELECTED TRANSITION ELEMENTS IN THE CHABAZITE-MOLTEN NANO3 SYSTEM,

    DTIC Science & Technology

    MINERALS, ION EXCHANGE, ION EXCHANGE, FUEL CELLS, LANTHANUM, DECOMPOSITION, EUROPIUM, IONS, EQUILIBRIUM(PHYSIOLOGY), NITRATES, COBALT, DISTRIBUTION, CERIUM, SILICATES, TRANSITION METALS, MOLTEN SALT NUCLEAR REACTORS.

  5. Compared electronic structure of negative ions M p C{/n -}: I. Normal elements in Hückel theory

    NASA Astrophysics Data System (ADS)

    Leleyter, M.

    1989-03-01

    Negative cluster ions M p C{/n -} (M normal element, n<10, p=1-4) produced by various experimental techniques from carbides show in their emission intensities a very strong even-odd effect according to the parity of the carbon atom number n. This is in particular the case when M=N, F, Cl ( p=1), M=H, Al, Si, S ( p=1, 2) or M=B ( p=1-4). The largest intensities of M p C{/n -} ions always take place for even n except in the cases of NC{/n -}, B2C{/n -} and Al2C{/n -}, for which the maxima of emission occur for odd n. This oscillating behaviour corresponds to alternations in the stability of the clusters which are mainly due to the fact that, in Pitzer and Clementi model (linear chains in the sp hybridization within the framework of Hückel theory), the HOMO (highest occupied molecular orbital) of the clusters lies in a double degenerate π level band: a cluster with a complete HOMO is always more stable than a cluster with a nearly empty HOMO. This result involves that the total number of π electrons is the main factor governing the parity of the stability alternations. Accordingly, since the knowledge of the π electron number requires the determination of the σ electron number too, these alternations enable us to infer a very likely electronic structure of the ions.

  6. An investigation of the optics of a 5-element electrostatic lens for use with a high brightness ion source

    NASA Astrophysics Data System (ADS)

    Colman, R. A.; Legge, G. J. F.

    1994-03-01

    The optics of a configuration consisting of a biased ion source exit canal, followed by a four-electrode electrostatic lens is investigated. This effectively operates as a five-electrode electrostatic lens (although two electrodes are in fact wired at the same potential). This lens displays three degrees of freedom in achieving a required beam focus. In particular, this lens is investigated to determine its optimal configuration for the present, low voltage ion source and its suitability for use with a high voltage field ionization ion source. The finite element method is used to calculate the electrostatic field in the lens, and optical properties are extracted from ray tracing. A full range of "accelerating" and "decelerating" focusing modes are analysed with a range of final to initial voltage ratios of between 1 and 16, and with and without a beam crossover inside the lens. It is found that aberrations are lowest for large initial acceleration, and with no beam crossover, with the optimal aberrations being relatively insensitive to the final electrode voltage. Calculations suggest, however, that the introduction of a high voltage field ionization source would almost certainly preclude the use of the optimal lens configuration in practice.

  7. A finite element simulation on transient large deformation and mass diffusion in electrodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    An, Yonghao; Jiang, Hanqing

    2013-10-01

    Lithium-ion batteries have attracted great deal of attention recently. Silicon is one of the most promising anode materials for high-performance lithium-ion batteries, due to its highest theoretical specific capacity. However, the short lifetime confined by mechanical failure in the silicon anode is now considered to be the biggest challenge in desired applications. High stress induced by the huge volume change due to lithium insertion/extraction is the main reason underlying this problem. Some theoretical models have been developed to address this issue. In order to properly implement these models, we develop a finite element based numerical method using a commercial software package, ABAQUS, as a platform at the continuum level to study fully coupled large deformation and mass diffusion problem. Using this method, large deformation, elasticity-plasticity of the electrodes, various spatial and temporal conditions, arbitrary geometry and dimension could be fulfilled. The interaction between anode and other components of the lithium ion batteries can also be studied as an integrated system. Several specific examples are presented to demonstrate the capability of this numerical platform.

  8. Fixation and imaging of biological elements: heavy metals, diffusible substances, ions, peptides, and lipids.

    PubMed

    Mizuhira, V; Hasegawa, H; Notoya, M

    2000-01-01

    We tested various fixation and analysis methods to demonstrate by electron microscopy elemental imaging in tissues and cells, i.e., soluble substances such as many kinds of ionic elements, water soluble low molecular peptides, and even organic solvent soluble substances such as lipids. For the ionic elements, we tested frozen dried or freeze-substituted methods and organic or inorganic special chemical precipitation methods combined with microwaved fixation methods. The data were analyzed with electron beam X-ray microanalysis, electron energy filtered imaging analysis, and electron microscope autoradiography. The data were demonstrated as elemental distribution images and were calculated quantitatively. For the soluble low molecular peptides, we developed a tannic acid and aldehyde method combined with microwaved fixation. We discuss the theoretical background of the tannic acid fixation and microwaved fixation methods. For the organic solvent soluble substances, i.e., lipids including steroids, we successfully tested the use of a mixed fixative of aldehyde and osmium, digitonization, and osmification with the use of p-phenylendiamine or imidazole. We also proposed some new ideal biotracers for electron beam X-ray microanalysis and electron energy filtered imaging analysis.

  9. Heavy-Ion Fusion Mechanism and Predictions of Super-Heavy Elements Production

    SciTech Connect

    Abe, Yasuhisa; Shen Caiwan; Boilley, David

    2009-08-26

    Fusion process is shown to firstly form largely deformed mono-nucleus and then to undergo diffusion in two-dimensions with the radial and mass-asymmetry degrees of freedom. Examples of prediction of residue cross sections are given for the elements with Z = 117 and 118.

  10. Combined element magnet production for the relativistic heavy ion collider (RHIC) at BNL

    SciTech Connect

    Mulhall, S.; Foelsche, H.; Ganetis, G.

    1995-05-01

    The production of 432 combined element magnets for RHIC is well underway. These magnets consist of a superconducting corrector, a quadrupole, and a sextupole combined into an integrated cold mass which is inserted into a cryostat. Production experiences as well as test results are reported.

  11. PSP toxin release from the cyanobacterium Raphidiopsis brookii D9 (Nostocales) can be induced by sodium and potassium ions.

    PubMed

    Soto-Liebe, Katia; Méndez, Marco A; Fuenzalida, Loreto; Krock, Bernd; Cembella, Allan; Vásquez, Mónica

    2012-12-01

    Paralytic shellfish poisoning (PSP) toxins are a group of naturally occurring neurotoxic alkaloids produced among several genera of primarily freshwater cyanobacteria and marine dinoflagellates. Although saxitoxin (STX) and analogs are all potent Na(+) channel blockers in vertebrate cells, the functional role of these compounds for the toxigenic microorganisms is unknown. Based upon the known importance of monovalent cations (such as sodium) in the maintenance of cellular homeostasis and ion channel function, we examined the effect of high extracellular concentrations of these ions on growth, cellular integrity, toxin production and release to the external medium in the filamentous freshwater cyanobacterium, Raphidiopsis brookii D9; a gonyautoxins (GTX2/3) and STX producing toxigenic strain. We observed a toxin export in response to high (17 mM) NaCl and KCl concentrations in the growth medium that was not primarily related to osmotic stress effects, compared to the osmolyte mannitol. Addition of exogenous PSP toxins with the same compositional profile as the one produced by R. brookii D9 was able to partially mitigate this effect of high Na⁺ (17 mM). The PSP toxin biosynthetic gene cluster (sxt) in D9 has two genes (sxtF and sxtM) that encode for a MATE (multidrug and toxic compound extrusion) transporter. This protein family, represented by NorM in the bacterium Vibrio parahaemolyticus, confers resistance to multiple cationic toxic agents through Na⁺/drug antiporters. Conserved domains for Na⁺ and drug recognition have been described in NorM. For the D9 sxt cluster, the Na⁺ recognition domain is conserved in both SxtF and SxtM, but the drug recognition domain differs between them. These results suggest that PSP toxins are exported directly in response to the presence of monovalent cations (Na⁺, K⁺) at least at elevated concentrations. Thus, the presence of both genes in the sxt cluster from strain D9 can be explained as a selective recognition

  12. Kinetic simulation of complex decomposition as a tool for the ion chromatographic determination of elemental speciation of less inert metal ions.

    PubMed

    Winter, Christian; Seubert, Andreas

    2016-01-15

    Species decomposition is an often occurring artefact during the chromatographic determination of elemental speciation. The decomposition follows a simple path to lower coordinated compounds. Therefore a simulation is developed for those decomposition reactions. The simulation separates the isochronal processes of the separation itself and the ongoing reaction and delivers thermodynamic and kinetic information about the species present in the original sample. This shifts the boundaries of separation based elemental speciation to less inert metal ions which are typically not analyzable by this approach. The less inert gallium monooxalato complex [GaOx](+) is used as example for testing the simulation software as this complex decomposes only to Ga(3+) and both species are retained on cation exchange columns. We extracted thermodynamic and kinetic information from flow rate experiments by the analysis of the peak areas in the chromatogram. The results show that some of our assumptions such as the irreversibility under the applied chromatographic conditions are not ultimately true, but good accordance of simulation and measured data was achieved.

  13. Determination of Zinc(II) Ions Released into Artificial Digestive Juices from Culinary-Medicinal Button Mushroom, Agaricus bisporus (Agaricomycetidae), Biomass of In Vitro Cultures Using an Anodic Stripping Voltammetry Method.

    PubMed

    Kala, Katarzyna; Muszynska, Bozena; Zajac, Magdalena; Krezalek, Remigiusz; Opoka, Wlodzimierz

    2016-01-01

    Zinc is one of those microelements that are essential for the proper functioning of the human body and must be supplemented in our food at a daily dose of 15 mg. It is well known that mushrooms accumulate elements; thus, in order to determine the extent of accumulation and the level of zinc released from mushrooms, in vitro cultures of Agaricus bisporus were established. The cultures were run on a modified Oddoux medium (a control culture) as well as on the same medium with the addition of zinc hydroaspartate (100 and 200 mg/L) and zinc sulfate (87.23 and 174.47 mg/L). These compounds were chosen to help estimate which form, organic or inorganic, results in a better assimilation of zinc(II) ions by biomass. As the next step, the level of zinc(II) ions released from the lyophilized biomass of in vitro cultures to the digestive juices, under thermal conditions of the human body (37°C), was determined. For this purpose, artificial digestive juices, imitating the composition of human digestive juices, were used. For determination of zinc(II) ions in the digestive tract, an anodic stripping voltammetry method was employed. The amount of zinc released into artificial saliva over 1 minute varied from 0.15 mg/100 g d.w. in the control culture to 2.35 mg/100 g d.w. in the biomass in the medium to which 200 mg/L zinc hydroaspartate had been added. Values were higher in gastric juice and depended on incubation time (2.66 to 30.63 mg/100 g d.w.). In intestinal juice, the highest value of the released zinc grew to 24.20 mg/100 g d.w. (biomass of A. bisporus in vitro cultures in medium with the addition of 200 mg/L zinc hydroaspartate). Total average amount of zinc released into artificial digestive juices was the highest (56.26 mg/100 g d.w.) from A. bisporus biomass of in vitro cultures in the medium to which 200 mg/L zinc hydroaspartate had been added.

  14. Atomic Data for Neutron-capture Elements I. Photoionization and Recombination Properties of Low-charge Selenium Ions

    NASA Technical Reports Server (NTRS)

    Sterling, N. C.; Witthoeft, Michael

    2011-01-01

    We present multi-configuration Breit-Pauli AUTOSTRUCTURE calculations of distorted-wave photoionization (PI) cross sections. and total and partial final-state resolved radiative recombination (RR) and dielectronic recombination (DR) rate coefficients for the first six ions of the trans-iron element Se. These calculations were motivated by the recent detection of Se emission lines in a large number of planetary nebulae. Se is a potentially useful tracer of neutron-capture nucleosynthesis. but accurate determinations of its abundance in photoionized nebulae have been hindered by the lack of atomic data governing its ionization balance. Our calculations were carried out in intermediate coupling with semi re1ativistic radial wavefunctions. PI and recombination data were determined for levels within the ground configuration of each ion, and experimental PI cross-section measurements were used to benchmark our results. For DR, we allowed (Delta)n = 0 core excitations, which are important at photoionized plasma temperatures. We find that DR is the dominant recombination process for each of these Se ions at temperatures representative of photoionized nebulae (approx.10(exp 4) K). In order to estimate the uncertainties of these data, we compared results from three different configuration-interaction expansions for each ion, and also tested the sensitivity of the results to the radial scaling factors in the structure calculations. We find that the internal uncertainties are typically 30-50% for the direct PI cross sections and approx.10% for the computed RR rate coefficients, while those for low-temperature DR can be considerably larger (from 15-30% up to two orders of magnitude) due to the unknown energies of near-threshold autoionization resonances. These data are available at the CDS, and fitting coefficients to the total RR and DR rate coefficients are presented. The results are suitable for incorporation into photoionization codes used to numerically simulate

  15. The evolution of complex type B Allende inclusion - An ion microprobe trace element study

    NASA Technical Reports Server (NTRS)

    Macpherson, Glenn J.; Crozaz, Ghislaine; Lundberg, Laura L.

    1989-01-01

    Results are presented of a detailed trace-element and isotopic analyses of the constituent phases in each of the major textural parts (mantle, core, and islands) of a Type B refractory inclusion, the USNM 5241 inclusion from Allende, first described by El Goresy et al. (1985). The REE data on 5241 were found to be largely consistent with a model in which the mantle and the core of 5241 formed sequentially out of a single melt by fractional crystallization. The numerical models of REE evolution in the 5241 melt, especially that of Eu, require that a significant mass of spinel-free island material was assimilated into the evolving melt during the last half of the solidification history of 5241. The trace element results pbtained thus strongly support the interpretation of El Goresy et al. (1985) that the spinel-free islands in the 5241 are trapped xenoliths.

  16. Trace element diffusivities in bone rule out simple diffusive uptake during fossilization but explain in vivo uptake and release.

    PubMed

    Kohn, Matthew J; Moses, Randolph J

    2013-01-08

    Diffusion rates of numerous trace elements in bone at 20 °C were determined using laser-ablation inductively coupled plasma mass spectrometry analysis of experimentally induced diffusion profiles. Diffusivities are about 1 order of magnitude slower than current semiquantitative geochemical views and about 1.5 orders of magnitude faster than indirect radiotracer estimates. Intrabone volume diffusion is too slow and too similar among many elements to explain trace element profiles in young fossils and archeological materials. Diffusivity differences among elements do, however, explain disparate biokinetic washout of Sr vs. Ba and of light vs. heavy rare earth elements (REEs). These results improve the understanding of the physical principles underlying biokinetic models and rates and mechanisms of trace element alteration of phosphatic tissues in paleontological, archeological, and crystal-chemical contexts. Recrystallization and transport limitations in soils explain trace element profiles in young fossils better than intrabone volume diffusion alone and imply that diffusion of REE and other trivalent cations is likely controlled by a common charge-compensating species rather than ionic radii or partition coefficients.

  17. Trace element diffusivities in bone rule out simple diffusive uptake during fossilization but explain in vivo uptake and release

    PubMed Central

    Kohn, Matthew J.; Moses, Randolph J.

    2013-01-01

    Diffusion rates of numerous trace elements in bone at 20 °C were determined using laser-ablation inductively coupled plasma mass spectrometry analysis of experimentally induced diffusion profiles. Diffusivities are about 1 order of magnitude slower than current semiquantitative geochemical views and about 1.5 orders of magnitude faster than indirect radiotracer estimates. Intrabone volume diffusion is too slow and too similar among many elements to explain trace element profiles in young fossils and archeological materials. Diffusivity differences among elements do, however, explain disparate biokinetic washout of Sr vs. Ba and of light vs. heavy rare earth elements (REEs). These results improve the understanding of the physical principles underlying biokinetic models and rates and mechanisms of trace element alteration of phosphatic tissues in paleontological, archeological, and crystal-chemical contexts. Recrystallization and transport limitations in soils explain trace element profiles in young fossils better than intrabone volume diffusion alone and imply that diffusion of REE and other trivalent cations is likely controlled by a common charge–compensating species rather than ionic radii or partition coefficients. PMID:23267089

  18. Surface Modification of NiTi Alloy via Cathodic Plasma Electrolytic Deposition and its Effect on Ni Ion Release and Osteoblast Behaviors

    NASA Astrophysics Data System (ADS)

    Yan, Ying; Cai, Kaiyong; Yang, Weihu; Liu, Peng

    2013-07-01

    To reduce Ni ion release and improve biocompatibility of NiTi alloy, the cathodic plasma electrolytic deposition (CPED) technique was used to fabricate ceramic coating onto a NiTi alloy surface. The formation of a coating with a rough and micro-textured surface was confirmed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy, respectively. An inductively coupled plasma mass spectrometry test showed that the formed coating significantly reduced the release of Ni ions from the NiTi alloy in simulated body fluid. The influence of CPED treated NiTi substrates on the biological behaviors of osteoblasts, including cell adhesion, cell viability, and osteogenic differentiation function (alkaline phosphatase), was investigated in vitro. Immunofluorescence staining of nuclei revealed that the CPED treated NiTi alloy was favorable for cell growth. Osteoblasts on CPED modified NiTi alloy showed greater cell viability than those for the native NiTi substrate after 4 and 7 days cultures. More importantly, osteoblasts cultured onto a modified NiTi sample displayed significantly higher differentiation levels of alkaline phosphatase. The results suggested that surface functionalization of NiTi alloy with ceramic coating via the CPED technique was beneficial for cell proliferation and differentiation. The approach presented here is useful for NiTi implants to enhance bone osseointegration and reduce Ni ion release in vitro.

  19. Effective inhibition of the early copper ion burst release with ultra-fine grained copper and single crystal copper for intrauterine device application.

    PubMed

    Xu, X X; Nie, F L; Wang, Y B; Zhang, J X; Zheng, W; Li, L; Zheng, Y F

    2012-02-01

    To solve the main problems of existing coarse grained copper (CG Cu) intrauterine devices (IUD)-namely burst release and a low transfer efficiency of the cupric ions during usage-ultra-fine grained copper (UFG Cu) and single crystal copper (SC Cu) have been investigated as potential substitutes. Their corrosion properties with CG Cu as a control have been studied in simulated uterine fluid (SUF) under different conditions using electrochemical measurement methods. Long-term immersion of UFG Cu, SC Cu and CG Cu samples in SUF at 37 °C have been studied for 300 days. A lower copper ion burst release and a higher efficiency release of cupric ions were observed for UFG Cu and SC Cu compared with CG Cu in the first month of immersion and 2 months later. The respective corrosion mechanisms for UFG Cu, SC Cu and CG Cu in SUF are proposed. In vitro biocompatibility tests show a better cellular response to UFG Cu and SC Cu than CG Cu. In terms of instantaneous corrosion behavior, long-term corrosion performance and in vitro biocompatibility, the three pure copper materials follow the order: UFG Cu>SC Cu>CG Cu, which indicates that UFG Cu could be the most suitable candidate material for intrauterine devices.

  20. Concentrations and sources of aerosol ions and trace elements during ANTCI-2003

    NASA Astrophysics Data System (ADS)

    Arimoto, R.; Zeng, T.; Davis, D.; Wang, Y.; Khaing, H.; Nesbit, C.; Huey, G.

    As part of the Antarctic Tropospheric Chemistry Investigation (ANTCI), bulk aerosol-particle samples collected at the South Pole were analyzed for nitrate, sulfate, methanesulfonate (MSA), selected trace elements and radionuclides. The samples were collected in the same manner as in the Investigation of Sulfur Chemistry in the Antarctic Troposphere (ISCAT) campaigns of 1998 and 2000. The ANTCI mean sulfate (124 ng m -3) and MSA (9.1 ng m -3) concentrations were comparable to those during ISCAT, but high MSA and sodium and high MSA/sulfate in late November/early December indicated pervasive maritime influences during that time. Trajectory analyses indicate that the Weddell Sea and the Southern Ocean near Wilkes Land were probable sources for the ocean-derived sulfate. The transport of marine air occurs mainly in the buffer layer or free troposphere, and the rapid oxidation of biogenic sulfur to SO 2 appears to be the basis for the observed low MSA/sulfate ratios. Elements typically associated with mineral dust (Al, Fe, K) and other elements with continental sources (Pb, Sb, Zn) had higher concentrations during ANTCI than ISCAT. The mean filterable nitrate (f-NO 3-) concentration (280 ng m -3) also was conspicuously higher than during ISCAT (39 and 150 ng m -3). Several peaks in f-NO 3- were synchronous with those for MSA and sulfate, but some samples had high f-NO 3- but neither high MSA nor sulfate. While there is some evidence that nitrate or nitric acid is transported to SP from distant sources, local emissions of nitrogen oxides from the snow are a far more important source overall.

  1. Negative ionization of the secondary ions of silver and gold sputtered from their elemental surfaces

    NASA Astrophysics Data System (ADS)

    Sindona, A.; Riccardi, P.; Maletta, S.; Rudi, S. A.; Falcone, G.

    2007-03-01

    Calculations of the ionization probabilities of Ag- and Au- particles, ejected during sputtering of clean Ag(1 0 0) and Au(1 0 0) surfaces, respectively, are reported. An effective one-electron theory is used to describe: the plane metal surface, with a projected band gap, the secondary emitted atom, whose charge state is investigated, and its nearest-neighbor substrate atom, put in motion by the collision cascade generated by the primary ion beam. Suitable rectilinear trajectories are selected to describe the motion of these two atoms outside the solid. A good agreement is found with van Der Heide's experiments (P.A.W. van Der Heide, Nucl. Instr. and Meth. B 157 (1999) 126).

  2. The cementogenic differentiation of periodontal ligament cells via the activation of Wnt/β-catenin signalling pathway by Li+ ions released from bioactive scaffolds.

    PubMed

    Han, Pingping; Wu, Chengtie; Chang, Jiang; Xiao, Yin

    2012-09-01

    Lithium (Li) has been widely used as a long-term mood stabilizer in the treatment of bipolar and depressive disorders. Li(+) ions are thought to enhance the remyelination of peripheral nerves and also stimulate the proliferation of neural progenitor cells and retinoblastoma cells via activation of the Wnt/β-catenin signalling pathway. Until now there have been no studies reporting the biological effects of released Li(+) in bioactive scaffolds on cemetogenesis in periodontal tissue engineering applications. In this study, we incorporated parts of Li(+) ions into the mesoporous bioactive glass (MBG) scaffolds and showed that this approach yielded scaffolds with a favourable composition, microstructure and mesopore properties for cell attachment, proliferation, and cementogenic differentiation of human periodontal ligament-derived cells (hPDLCs). We went on to investigate the biological effects of Li(+) ions themselves on cell proliferation and cementogenic differentiation. The results showed that 5% Li(+) ions incorporated into MBG scaffolds enhanced the proliferation and cementogenic differentiation of hPDLCs on scaffolds, most likely via activation of Wnt/β-catenin signalling pathway. Further study demonstrated that Li(+) ions by themselves significantly enhanced the proliferation, differentiation and cementogenic gene expression of PDLCs. Our results indicate that incorporation of Li(+) ions into bioactive scaffolds is a viable means of enhancing the Wnt canonical signalling pathway to stimulate cementogenic differentiation of PDLCs.

  3. Effects of niobium ions released from calcium phosphate invert glasses containing Nb2O5 on osteoblast-like cell functions.

    PubMed

    Obata, Akiko; Takahashi, Yoshiaki; Miyajima, Tomohiro; Ueda, Kyosuke; Narushima, Takayuki; Kasuga, Toshihiro

    2012-10-24

    The effects of niobium ions released from 60CaO-30P(2)O(5)-(10-x)Na(2)O-xNb(2)O(5) (mol %, x = 0-10) glasses on MC3T3-E1 cell functions were evaluated by culture tests with two systems; cell culture on glass plates, or in culture media containing glass extracts. Alkaline phosphatase (ALP) activity in the cells cultured on the glass plates containing 3 and 5 mol % of Nb(2)O(5) was significantly higher than that on the Nb(2)O(5)-free glass, although proliferation was not enhanced on all glasses containing Nb(2)O(5). Cells cultured in the medium containing 3 × 10(-7) M niobium ions showed the highest ALP activity in comparison with other Nb-containing media or normal medium, regardless of the presence of osteogenic factors (ascorbic acid, β-glycerophosphate and dexamethasone) in the media. Calcium deposition by the cells cultured in the medium containing 3 × 10(-7) M niobium ions was twice as high as those cultured in medium containing no niobium ions. The effects of niobium ions were thought to depend on ion concentration, and to enhance differentiation and mineralization of osteogenic cells rather than their initial adhesion or proliferation.

  4. [Corrosion of Ag-Pd-Cu alloys in saline solution. Amount of released elements and electrochemical corrosion].

    PubMed

    Kitaoka, M

    1989-03-01

    The effect of the Pd content on corrosion and tarnish resistance in twelve experimental alloys was investigated. The alloys were prepared with a composition of Pd content from 20.1 to 30.1 at %. The composition of the alloys Ag-20% Pd, Ag-25% Pd and Ag-30% Pd was varied by adding Cu 5 wt%, 10 wt% and 15 wt% to each of them. The corrosion resistance was estimated by the amount of the released Ag, Cu and by electrochemical corrosion behavior in 0.86% NaCl solution at 37 degrees C. The tarnish resistance was assessed using a spectrophotometer. The test solutions included 0.86% NaCl solution, 0.1% Na2S solution and a mixture of 1.0% lactic acid and 0.1% Na2S, all at 37 degrees C, in sealed containers. The results are summarized as follows. The larger the amount of Pd in Ag-Pd binary alloys and Ag-Pd-Cu ternary alloys, the more stable was the release and the release rate of Ag, Cu and corrosion resistance increased in 0.86% NaCl solution. The addition of Cu to Ag-Pd binary alloys increased the release and release rate of Ag, but there was a shift of the rest potential in the noble direction. A relationship was found between the amount of Ag and Cu released from Ag-Pd-Cu ternary alloys. In this study, an increase in corrosion resistance was observed when the content of Pd in Ag-Pd binary alloys was 25 wt%. Furthermore, it was also observed that Ag-Pd-Cu ternary alloys need an additional 30 wt% Pd for corrosion resistance. Moreover, the addition of Cu must be kept lower than 10 wt%. The tarnish resistance of the twelve experimental alloys was good in 0.86% NaCl solution but was barely improved with increased in the Pd content in sulfide solution. The correlation between electrochemical corrosion behavior and tarnish resistance was not significant, but the correlation between the amount of Ag, Cu release from Ag-Pd-Cu ternary alloys and tarnish resistance was remarkable.

  5. Trace element distribution between clinopyroxene and garnet in gabbroic rocks of the deep crust: An ion microprobe study

    NASA Astrophysics Data System (ADS)

    Mazzucchelli, Maurizio; Rivalenti, Giorgio; Vannucci, Riccardo; Bottazzi, Plero; Ottolini, Luisa; Hofmann, Albrecht W.; Sinigol, Silvano; Demarchin, Gabriella

    1992-06-01

    Clinopyroxenes and garnets from gabbroic rocks of the Ivrea Verbano mafic complex have been analyzed by electron microprobe for major elements and by ion microprobe for REE, Sc, Cr, Ti, V, Zr, Na, and Sr content. The samples represent two petrographic types: in the first, garnet is formed by subsolidus reaction and occurs in coronas (c-type); in the other, garnet occurs as large porphyroblasts (p-type) and may have been a phase on the liquidus. Clinopyroxenes and garnets are unzoned (with one exception) for major and trace elements, suggesting that, in general, equilibrium has been attained under granulite facies conditions as indicated by the geothermometers. Clinopyroxene, although affected in its HREE and Sc content by the coexistence with garnet, has REE patterns which vary, along with the bulk rock patterns, stratigraphically upwards from LREE-depleted to LREE-enriched. Trace element distribution coefficients ( D) between clinopyroxene and garnet, as measured in the p-type assemblages, vary systematically with major-element compositional parameters such as FeO, MgO, FeO/MgO, Al 2O 3, Na 2O, and apparent equilibration temperature. In addition, the overall pattern of REE partitioning, D(Ce) to D(Yb), is significantly steeper than those found in previously published estimates, except when these were determined on exceptionally carefully prepared mineral separates. The D values determined on c-type assemblages are comparatively erratic and appear to depend on the modal gnt/cpx ratio. This feature is tentatively attributed to failure to achieve complete equilibrium during slow cooling when the corona structures were formed. Subsolidus reequilibration between phases has generally obliterated the igneous phase chemistry of the rocks sufficiently so that the composition of the parent liquid cannot be determined from those of the constituent minerals even when these represent original "phenocrysts."

  6. 3,3'-Dihydroxyisorenieratene prevents UV-induced formation of reactive oxygen species and the release of protein-bound zinc ions in human skin fibroblasts.

    PubMed

    Lutter, Kaya; De Spirt, Silke; Kock, Sebastian; Kröncke, Klaus-Dietrich; Martin, Hans-Dieter; Wagener, Tanja; Stahl, Wilhelm

    2010-02-01

    3,3'-Dihydroxyisorenieratene (DHIR) is a structurally unusual carotenoid exhibiting bifunctional antioxidant properties. It is synthesized by Brevibacterium linens, used in dairy industry for the production of red smear cheeses. The compound protects cellular structures against photo-oxidative damage and inhibits the UV-dependent formation of thymidine dimers. Here we show that DHIR prevents a UV-induced intracellular release of zinc ions from proteins in human dermal fibroblasts. The effect is correlated with a decreased formation of intracellular reactive oxygen species. In contrast, zinc release from cellular proteins induced by hyperthermia is not affected by pretreatment of cells with the antioxidant DHIR. It is suggested that the intracellular zinc release upon UV irradiation is due to oxidative modifications of the zinc ligands in proteins (e.g. cysteine) and that protection by DHIR is due to intracellular scavenging of reactive oxygen species generated in photo-oxidation.

  7. AMS of heavy elements with an ECR ion source and the ATLAS linear accelerator.

    SciTech Connect

    Paul, M.; Berkovits, D.; Ahmad, I.; Borasi, F.; Caggiano, J.; Davids, C.; Greene, J.; Harss, B.; Heinz, A.; Henderson, D. J.; Henning, W.; Jiang, C. L.; Pardo, R.; Rehm, K. E.; Rejoub, R.; Seweryniak, D.; Sonzogni, A.; Uusitalo, J.; Vondrasek, R.

    1999-12-13

    Understanding the fate of heavy-metal contaminants in the environment is of fundamental importance in the development and evaluation of effective remediation and sequestration strategies. Among the factors influencing the transport of these contaminants are their chemical speciation and the chemical and physical attributes of the surrounding medium. Bacteria and the extracellular material associated with them are thought to play a key role in determining a contaminant's speciation and thus its mobility in the environment. In addition, the microenvironment at and adjacent to actively metabolizing cell surfaces can be significantly different from the bulk environment. Thus, the spatial distribution and chemical speciation of contaminants and elements that are key to biological processes must be characterized at micron and submicron resolution in order to understand the microscopic physical, geological, chemical, and biological interfaces that determine a contaminant's macroscopic fate. Hard x-ray microimaging is a powerful technique for the element-specific investigation of complex environmental samples at the needed micron and submicron resolution. An important advantage of this technique results from the large penetration depth of hard X-rays in water. This advantage minimizes the requirements for sample preparation and allows the detailed study of hydrated samples. This paper presents results of studies of the spatial distribution of naturally occurring metals and a heavy-metal contaminant (Cr) in and near hydrated bacteria (Pseudomonas fluorescens) in the early stages of biofilm development performed at the Advanced Photon Source Sector 2 X-ray microscopy beamline.

  8. Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)-peroxo complexes

    NASA Astrophysics Data System (ADS)

    Bang, Suhee; Lee, Yong-Min; Hong, Seungwoo; Cho, Kyung-Bin; Nishida, Yusuke; Seo, Mi Sook; Sarangi, Ritimukta; Fukuzumi, Shunichi; Nam, Wonwoo

    2014-10-01

    Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)-peroxo complexes that bind redox-inactive metal ions, (TMC)FeIII-(μ,η2:η2-O2)-Mn+ (Mn+ = Sr2+, Ca2+, Zn2+, Lu3+, Y3+ and Sc3+; TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca2+ and Sr2+ complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities of complexes formed with stronger Lewis acidities were found to be markedly different. Complexes that contain Ca2+ or Sr2+ ions were oxidized by an electron acceptor to release O2, whereas the release of O2 did not occur for complexes that bind stronger Lewis acids. We discuss these results in the light of the functional role of the Ca2+ ion in the oxidation of water to dioxygen by the oxygen-evolving complex.

  9. Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)–peroxo complexes

    DOE PAGES

    Bang, Suhee; Lee, Yong -Min; Hong, Seungwoo; ...

    2014-09-14

    Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)–peroxo complexes that bind redox-inactive metal ions, (TMC)FeIII–(μ,η2:η2-O2)–Mn+ (Mn+ = Sr2+, Ca2+, Zn2+, Lu3+, Y3+ and Sc3+; TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca2+ and Sr2+ complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities of complexes formed with stronger Lewis acidities were found to be markedly different. Inmore » conclusion, complexes that contain Ca2+ or Sr2+ ions were oxidized by an electron acceptor to release O2, whereas the release of O2 did not occur for complexes that bind stronger Lewis acids. Furthermore, we discuss these results in the light of the functional role of the Ca2+ ion in the oxidation of water to dioxygen by the oxygen-evolving complex.« less

  10. Elemental abundance and spectral variations of the suprathermal heavy ion populations in interplanetary space

    NASA Astrophysics Data System (ADS)

    Al Dayeh, Maher Abdul Hamid

    Solar energetic particles (SEPs) associated with coronal mass ejections (CMEs) are usually accompanied by large particle intensities and magnetic clouds that often cause terrestrial geomagnetic storms. These storms present a danger to many aspects on earth, from satellites and communications, to power and pipelines, in addition to forming a danger to astronauts in space. The scientific objectives for studying SEPs in this dissertation are twofold. First is to improve our understanding of SEP sources, acceleration, and propagation in interplanetary (IP) space. The second is to improve our capabilities in space weather prediction. This dissertation investigates the source material of SEPs through detailed analysis of the temporal, compositional, and spectral variations of heavy ion species (mass > 4 nucleons) at the energy range ~0.045 MeV/nuc -10 MeV/nuc from December 1995 to December 2006, thus covering all of solar cycle 23. Data used in this dissertation are mainly from ULEIS and STEP time-of-flight mass spectrometers onboard the ACE (launched 08/1997) and Wind (launched 11/1994) spacecraft respectively. Observations reported in this work show that daily variations of low-energy heavy ions (~0.12 MeV/nucleon) in IP space are correlated with the solar cycle. Such dependence is not seen in a set of gradual SEP events. However, these events show large event-to-event fluctuations. This suggests that there exist multiple scenarios by which the seed material is injected into accelerating IP shocks, these are: (i) remnant material from previous flares that remain in IP space or get continuously replenished by frequent flare activity; (ii) direct contributions from accompanying flares, i.e., particles that escape from the flare through open field lines could encounter the CME shock, get re- accelerated and cause an enhancement in the heavy-ion abundances; (iii) the same or nearby active regions on the Sun produce suprathermal particles with flare-like composition that

  11. Major-ion, nutrient, and trace-element concentrations in the Steamboat Creek basin, Oregon, 1996

    USGS Publications Warehouse

    Rinella, Frank A.

    1998-01-01

    Bottom-sediment concentrations of antimony, arsenic, cadmium, copper, lead, mercury, zinc, and organic carbon were largest in City Creek. In City Creek and Horse Heaven Creek, concentrations for 11 constituents--antimony, arsenic, cadmium, copper, lead, manganese (Horse Heaven Creek only), mercury, selenium, silver, zinc, and organic carbon (City Creek only)--exceeded concentrations considered to be enriched in streams of the nearby Willamette River Basin, whereas in Steamboat Creek only two trace elements--antimony and nickel--exceeded Willamette River enriched concentrations. Bottom-sediment concentrations for six of these constituents in City Creek and Horse Heaven Creek--arsenic, cadmium, copper, lead, mercury, and zinc--also exceeded interim Canadian threshold effect level (TEL) concentrations established for the protection of aquatic life, whereas only four constituents between Singe Creek and Steamboat Creek--arsenic, chromium, copper (Singe Creek only), and nickel--exceeded the TEL concentrations.

  12. Chemical characterization of high-temperature arc gasification slag with a focus on element release in the environment.

    PubMed

    Roessler, Justin G; Oehmig, Wesley N; Blaisi, Nawaf I; Townsend, Timothy G

    2014-07-15

    High-temperature arc gasification (HTAG) has been proposed as a viable technology for the generation of energy and the production of saleable byproducts from municipal solid waste (MSW). Total concentrations of elements in HTAG slag were assessed and indicated a high partitioning of trace elements (Pb, Cd, and As) into the flue gas, an issue of concern when assessing the air pollution control residues (APCR) status as a hazardous waste. Hazardous waste leaching tests [such as the toxicity characteristic leaching procedure (TCLP)] were performed and confirmed that the slag did not meet U.S. criteria for a hazardous waste. Leaching was assessed using batch and column tests; the results revealed that Sb and Al were elevated in respect to risk-based regulatory thresholds. Slag samples were carbonated to simulate weathering effects, and although leachable concentrations of Al did decrease by an order of magnitude, Sb concentrations were found to increase. Low total concentrations of certain trace elements (As, Cd, and Pb), with respect to MSW incineration bottom ashes support the potential for reuse of HTAG slag; however, leaching of elements (Pb, Al, and Sb) in batch and column tests indicate that proper engineering controls would need to be taken to ensure protection of water supplies in a reuse application.

  13. Stopping power for low-velocity heavy ions: (0-1.0)-MeV/nucleon Mg ions in 17 (Z=22-79) elemental solids

    NASA Astrophysics Data System (ADS)

    Arstila, K.; Keinonen, J.; Tikkanen, P.

    1990-04-01

    The stopping power for 24,26Mg ions in 17 (Z=22-79) elemental solids has been studied in the energy region 0-1.0 MeV/nucleon by application of the Doppler-shift attenuation method. At velocities 2v0

  14. New and notable ion-channels in the sarcoplasmic/endoplasmic reticulum: do they support the process of intracellular Ca2+ release?

    PubMed Central

    Takeshima, Hiroshi; Venturi, Elisa; Sitsapesan, Rebecca

    2015-01-01

    Intracellular Ca2+ release through ryanodine receptor (RyR) and inositol trisphosphate receptor (IP3R) channels is supported by a complex network of additional proteins that are located in or near the Ca2+ release sites. In this review, we focus, not on RyR/IP3R, but on other ion-channels that are known to be present in the sarcoplasmic/endoplasmic reticulum (ER/SR) membranes. We review their putative physiological roles and the evidence suggesting that they may support the process of intracellular Ca2+ release, either indirectly by manipulating ionic fluxes across the ER/SR membrane or by directly interacting with a Ca2+-release channel. These channels rarely receive scientific attention because of the general lack of information regarding their biochemical and/or electrophysiological characteristics makes it difficult to predict their physiological roles and their impact on SR Ca2+ fluxes. We discuss the possible role of SR K+ channels and, in parallel, detail the known biochemical and biophysical properties of the trimeric intracellular cation (TRIC) proteins and their possible biological and pathophysiological roles in ER/SR Ca2+ release. We summarise what is known regarding Cl− channels in the ER/SR and the non-selective cation channels or putative ‘Ca2+ leak channels’, including mitsugumin23 (MG23), pannexins, presenilins and the transient receptor potential (TRP) channels that are distributed across ER/SR membranes but which have not yet been fully characterised functionally. PMID:26228553

  15. Influence of residual pressure and ion implantation on the structure, elemental composition, and properties of (TiZrAlYNb)N nitrides

    NASA Astrophysics Data System (ADS)

    Pogrebnjak, A. D.; Yakushchenko, I. V.; Sobol', O. V.; Beresnev, V. M.; Kupchishin, A. I.; Bondar, O. V.; Lisovenko, M. A.; Amekura, H.; Kono, K.; Oyoshi, K.; Takeda, Y.

    2015-08-01

    The nitrides of high-entropy alloys, (TiZrAlYNb)N, fabricated by cathodic vacuum arc evaporation are studied with electron microscopy, atomic force microscopy, laser scanning microscopy; energy-dispersive X-ray analysis, X-ray phase analysis, time-of-flight secondary-ion mass spectrometry; and hardness measurements. It is found that the deposition parameters influence the structure, surface morphology, element distribution, and mechanical properties. The structural—phase state of the coatings before and after the ion implantation of heavy negative gold ions Au- are compared.

  16. Self-diffusion coefficients of the trivalent f-element ion series in dilute and moderately dilute aqueous solutions: A comparative study between europium, gadolinium, terbium and berkelium

    NASA Astrophysics Data System (ADS)

    Rafik, Besbes; Noureddine, Ouerfelli; Abderabbou, Abdelmanef; Habib, Latrous

    2010-03-01

    We have continued the studies on the trivalent ions of the 4f and 5f elements. In this paper, we compare the transport properties (self-diffusion coefficient) of the trivalent aquo ions over two ranges of concentrations (0 — 2×10-3M) and (2×10-3 — 1.5M). Self-diffusion coefficients, D, of the trivalent f-element aquo ion series have been determined in aqueous background electrolytes of Gd(NO3)3 and Nd(ClO4)3, at pH=2.5 (HNO3, HClO4) and at 25°C using the open-end capillary method (O.E.C.M.). This method measures the transportation time of ions across a fixed distance. In this paper, we complete a measurement of self-diffusion coefficient for terbium. We optimized the pH to avoid hydrolysis, ion-pairing and complexation of the trivalent 4f and 5f ions. The variation of D versus √C is not linear for dilute solutions (0 — 2×10-3M) and quasi-linear in moderate concentrations (C<=1.5 M). Similar behavior was observed for Tb, as compared with those for Bk, Eu and Gd. We complete the comparison variation of D/D° versus √C for all studied 4f and 5f elements from concentration 0 to 1.5M and we obtained the same variation with √C for all studied elements. All 4f and 5f elements studied follow the Nernst-Hartley expression.

  17. Effect of pH on the release of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resins collected from operating nuclear power stations

    SciTech Connect

    McIsaac, C.V.; Akers, D.W.; McConnell, J.W. )

    1991-06-01

    Data are presented on the physical stability and leachability of radionuclides and chelating agents from cement-solidified decontamination ion-exchange resin wastes collected from two operating commercial light water reactors. Small-scale waste--form specimens collected during solidifications performed at the Brunswick Steam Electric Plant Unit 1 and at the James A. FitzPatrick Nuclear Power Station were leach-tested and subjected to compressive strength testing in accordance with the Nuclear Regulatory Commission's Technical Position on Waste Form'' (Revision 1). Samples of untreated resin waste collected from each solidification vessel before the solidification process were analyzed for concentrations of radionuclides, selected transition metals, and chelating agents to determine the quantities of these chemicals in the waste-form specimens. The chelating agents included oxalic, citric, and picolinic acids. In order to determine the effect of leachant chemical composition and pH on the stability and leachability of the waste forms, waste-form specimens were leached in various leachants. Results of this study indicate that differences in pH do not affect releases from cement-solidified decontamination ion-exchange resin waste forms, but that differences in leachant chemistry and the presence of chelating agents may affect the releases of radionuclides and chelating agents. Also, this study indicates that the cumulative releases of radionuclides and chelating agents are similar for waste- form specimens that decomposed and those that retained their general physical form. 36 refs., 60 figs., 28 tabs.

  18. Zinc-sensitive MRI contrast agent detects differential release of Zn(II) ions from the healthy vs. malignant mouse prostate

    PubMed Central

    Clavijo Jordan, M. Veronica; Lo, Su-Tang; Chen, Shiuhwei; Preihs, Christian; Chirayil, Sara; Zhang, Shanrong; Kapur, Payal; Li, Wen-Hong; De Leon-Rodriguez, Luis M.; Lubag, Angelo J. M.; Rofsky, Neil M.; Sherry, A. Dean

    2016-01-01

    Many secretory tissues release Zn(II) ions along with other molecules in response to external stimuli. Here we demonstrate that secretion of Zn(II) ions from normal, healthy prostate tissue is stimulated by glucose in fasted mice and that release of Zn(II) can be monitored by MRI. An ∼50% increase in water proton signal enhancement is observed in T1-weighted images of the healthy mouse prostate after infusion of a Gd-based Zn(II) sensor and an i.p. bolus of glucose. Release of Zn(II) from intracellular stores was validated in human epithelial prostate cells in vitro and in surgically exposed prostate tissue in vivo using a Zn(II)-sensitive fluorescent probe known to bind to the extracellular surface of cells. Given the known differences in intracellular Zn(II) stores in healthy versus malignant prostate tissues, the Zn(II) sensor was then evaluated in a transgenic adenocarcinoma of the mouse prostate (TRAMP) model in vivo. The agent proved successful in detecting small malignant lesions as early as 11 wk of age, making this noninvasive MR imaging method potentially useful for identifying prostate cancer in situations where it may be difficult to detect using current multiparametric MRI protocols. PMID:27562169

  19. Zinc-sensitive MRI contrast agent detects differential release of Zn(II) ions from the healthy vs. malignant mouse prostate.

    PubMed

    Clavijo Jordan, M Veronica; Lo, Su-Tang; Chen, Shiuhwei; Preihs, Christian; Chirayil, Sara; Zhang, Shanrong; Kapur, Payal; Li, Wen-Hong; De Leon-Rodriguez, Luis M; Lubag, Angelo J M; Rofsky, Neil M; Sherry, A Dean

    2016-09-13

    Many secretory tissues release Zn(II) ions along with other molecules in response to external stimuli. Here we demonstrate that secretion of Zn(II) ions from normal, healthy prostate tissue is stimulated by glucose in fasted mice and that release of Zn(II) can be monitored by MRI. An ∼50% increase in water proton signal enhancement is observed in T1-weighted images of the healthy mouse prostate after infusion of a Gd-based Zn(II) sensor and an i.p. bolus of glucose. Release of Zn(II) from intracellular stores was validated in human epithelial prostate cells in vitro and in surgically exposed prostate tissue in vivo using a Zn(II)-sensitive fluorescent probe known to bind to the extracellular surface of cells. Given the known differences in intracellular Zn(II) stores in healthy versus malignant prostate tissues, the Zn(II) sensor was then evaluated in a transgenic adenocarcinoma of the mouse prostate (TRAMP) model in vivo. The agent proved successful in detecting small malignant lesions as early as 11 wk of age, making this noninvasive MR imaging method potentially useful for identifying prostate cancer in situations where it may be difficult to detect using current multiparametric MRI protocols.

  20. Water quality in the Tibetan Plateau: major ions and trace elements in the headwaters of four major Asian rivers.

    PubMed

    Huang, Xiang; Sillanpää, Mika; Gjessing, Egil T; Vogt, Rolf D

    2009-12-01

    The Tibetan Plateau covers an area of about one fourth of Europe, has an average elevation over 4000m above sea level, and is the water sources for about 40% of world's population. In order to foresee future changes in water quality, it is important to understand what pressures are governing the spatial variation in water chemistry. In this paper the chemistry including major ions and trace elements in the headwaters of four major Asian rivers (i.e. the Salween, Mekong, Yangtze River and Yarlung Tsangpo) in the Tibetan Plateau was studied. The results showed that the content of dissolved salts in these Tibetan rivers was relatively high compared to waters from other parts of the world. The chemical composition of the four rivers were rather similar, with Ca(2+) and HCO(3)(-) being the dominating ions. The exception was the Yangtze River on the Plateau, which was enriched in Na(+), Cl(-), SO(4)(2-) and Li due to silicate weathering followed by strong evaporation caused by a negative water balance, dissolution of evaporites in the catchment and some drainage from saline lakes. The concentrations of heavy metals (Cu, Co, Cr, Ni, Cd, Pb, and Hg) and As, NH(4)(+) were generally low in all the rivers. Anthropogenic impacts on the quality of the rivers were identified at a few locations in the Mekong River and Yarlung Tsangpo basins. Generally, the main spatial variation in chemical compositions of these under studied rivers was found to be governed mainly by difference in geological variation and regional climatic-environment. Climate change is, therefore, one of main determining factors on the water chemical characteristics of these headwaters of Asian major rivers in the Tibetan Plateau.

  1. Mechanical properties of UO2 thin films under heavy ion irradiation using nanoindentation and finite element modeling

    NASA Astrophysics Data System (ADS)

    Elbakhshwan, Mohamed S.; Miao, Yinbin; Stubbins, James F.; Heuser, Brent J.

    2016-10-01

    The mechanical response of UO2 to irradiation is becoming increasingly important due to the shift to higher burn-up rates in the next generation of nuclear reactors. In the current study, thin films of UO2 were deposited on YSZ substrates using reactive-gas magnetron sputtering. Nanoindentation was used to measure the mechanical properties of the as-grown and irradiated films. Finite element modeling was used to account for the substrate effect on the measurements. In order to study the effect of displacement cascades accompanying gas bubbles, 5000 Å UO2 films were irradiated with 600 keV Kr+ ions at 25 °C and 600 °C. These irradiation conditions were used to confine radiation damage effects and implanted gas within the film. Results showed an increase in the film hardness and yield strength with dose, while elastic modulus initially decreased with irradiation and then kept increasing with dose. The change in hardness and elastic modulus is attributed to the introduction of gas bubbles and displacement cascade damage. Irradiation at 600 °C resulted in a decrease in the hardness and elastic modulus after irradiation using 600 keV Kr+ at a dose of 1E14 ions/cm2. Both hardness and elastic modulus then increased with irradiation dose. This behavior is attributed to recrystallization during irradiation at 600 °C and the formation of nanocrystallite regions with diameter and density that increase with dose. The calculation of the critical resolved shear stress (CRSS) demonstrated that nanocrystals are the primary cause for film hardening based on the Orowan hardening mechanism.

  2. Toxicity of cobalt-chromium nanoparticles released from a resurfacing hip implant and cobalt ions on primary human lymphocytes in vitro.

    PubMed

    Posada, Olga M; Tate, R J; Grant, M H

    2015-06-01

    Adverse tissue responses to prostheses wear particles and released ions are important contributors to hip implant failure. In implant-related adverse reactions T-lymphocytes play a prominent role in sustaining the chronic inflammatory response. To further understand the involvement of lymphocytes in metal-on-metal (MoM) implant failure, primary human lymphocytes were isolated and treated with cobalt-chromium (Co-Cr) wear debris and Co ions, individually, and in combination, for 24, 48 and 120 h. There was a significant increase in cell number where debris was present, as measured by the Neutral Red assay. Interleukin-6 (IL-6), interferon-γ (IFN-γ) and tumour necrosis factor-α (TNF-α) secretion levels significantly decreased in the presence of metal particles, as measured by ELISA. Interleukin-2 (IL-2) secretion levels were significantly decreased by both debris and Co ions. Flow cytometry analysis showed that the metal nanoparticles induced a significant increase in apoptosis after 48-h exposure. This investigation showed that prolonged exposure (120 h) to metal debris induces lymphocyte proliferation, suggesting that activation of resting lymphocytes may have occurred. Although cytokine production was affected mainly by metal debris, cobalt toxicity may also modulate IL-2 secretion, and even Co ion concentrations below the MHRA guideline levels (7 ppb) may contribute to the impairment of immune regulation in vivo in patients with MoM implants.

  3. Dual drug load and release behavior on ion-exchange fiber: influencing factors and prediction method for precise control of the loading amount.

    PubMed

    Yuan, Jing; Gao, Yanan; Liu, Tiaotiao; Wang, Xinyu; Liu, Hongzhuo; Li, Sanming

    2015-01-01

    Ion-exchange fiber undergoes a stoichiometric exchange reaction and has large exchange capability, which makes it a promising candidate as a multiple drug carrier. Because combinatorial effects can act synergistically, additively or antagonistically depending on the ratio of the agents being combined, the objective of this study was to learn the dual drug loading of ion-exchange fiber and develop a mathematical method for precisely control of the loading amount. Atenolol and Gatifloxacin, with different loading behaviors into strong cationic ion-exchange fiber ZB-1, were used to build a representative of dual loading. Not suitable pH value of drug solutions could make simultaneous loading fail, while the change of drug solution volume hardly affected the equilibrium. Ion-exchange groups occupied by the drug which owned lower affinity to fiber could be grabbed by the higher affinity drug, indicating the existence of competition between drugs. Thermodynamic model was introduced to guide the loading prediction and a favorable relevance had been shown between determined and predicted data. The release behaviors of each drug from dual drug-fiber complex were similar to those from single drug-fiber complexes.

  4. Redox-inactive metal ions modulate the reactivity and oxygen release of mononuclear non-haem iron(III)–peroxo complexes

    SciTech Connect

    Bang, Suhee; Lee, Yong -Min; Hong, Seungwoo; Cho, Kyung -Bin; Nishida, Yusuke; Seo, Mi Sook; Sarangi, Ritimukta; Fukuzumi, Shunichi; Nam, Wonwoo

    2014-09-14

    Redox-inactive metal ions that function as Lewis acids play pivotal roles in modulating the reactivity of oxygen-containing metal complexes and metalloenzymes, such as the oxygen-evolving complex in photosystem II and its small-molecule mimics. Here we report the synthesis and characterization of non-haem iron(III)–peroxo complexes that bind redox-inactive metal ions, (TMC)FeIII–(μ,η22-O2)–Mn+ (Mn+ = Sr2+, Ca2+, Zn2+, Lu3+, Y3+ and Sc3+; TMC, 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). We demonstrate that the Ca2+ and Sr2+ complexes showed similar electrochemical properties and reactivities in one-electron oxidation or reduction reactions. However, the properties and reactivities of complexes formed with stronger Lewis acidities were found to be markedly different. In conclusion, complexes that contain Ca2+ or Sr2+ ions were oxidized by an electron acceptor to release O2, whereas the release of O2 did not occur for complexes that bind stronger Lewis acids. Furthermore, we discuss these results in the light of the functional role of the Ca2+ ion in the oxidation of water to dioxygen by the oxygen-evolving complex.

  5. Elemental compositions of PM10-2.5 and PM2.5 aerosols of a Nigerian urban city using ion beam analytical techniques

    NASA Astrophysics Data System (ADS)

    Ezeh, G. C.; Obioh, I. B.; Asubiojo, O. I.; Chiari, M.; Nava, S.; Calzolai, G.; Lucarelli, F.; Nuviadenu, C. K.

    2014-09-01

    The paucity of data on air quality studies in Nigeria prompted us to commence the sampling of particulate matter (PM10-2.5 and PM2.5) in Mushin Lagos, Nigeria. Both size-segregated fractions were collected using a double staged ‘Gent' stack filter unit sampler. Elemental characterization was carried out by Particle Induced X-ray Emission (PIXE) and Proton Induced γ-ray Emission (PIGE) techniques using an external ion beam set-up. Twenty-four elements (Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Se, Br, Rb, Sr, Zr, Cs and Pb) were detected in both fractions and their concentrations were assessed. A study of their inter-elemental correlations indicated that some elements could have common source origins or similar chemical properties while enrichment factors (EF) displayed that most elements emanated from anthropogenic sources. Source apportionment studies are thus recommended.

  6. A two-state model for the dynamics of the pyrophosphate ion release in bacterial RNA polymerase.

    PubMed

    Da, Lin-Tai; Pardo Avila, Fátima; Wang, Dong; Huang, Xuhui

    2013-04-01

    The dynamics of the PPi release during the transcription elongation of bacterial RNA polymerase and its effects on the Trigger Loop (TL) opening motion are still elusive. Here, we built a Markov State Model (MSM) from extensive all-atom molecular dynamics (MD) simulations to investigate the mechanism of the PPi release. Our MSM has identified a simple two-state mechanism for the PPi release instead of a more complex four-state mechanism observed in RNA polymerase II (Pol II). We observed that the PPi release in bacterial RNA polymerase occurs at sub-microsecond timescale, which is ∼3-fold faster than that in Pol II. After escaping from the active site, the (Mg-PPi)(2-) group passes through a single elongated metastable region where several positively charged residues on the secondary channel provide favorable interactions. Surprisingly, we found that the PPi release is not coupled with the TL unfolding but correlates tightly with the side-chain rotation of the TL residue R1239. Our work sheds light on the dynamics underlying the transcription elongation of the bacterial RNA polymerase.

  7. Separation of berkelium (IV) from trivalent transplutonium elements on ion-exchangers in solutions of phosphoric acid

    SciTech Connect

    Guseva, L.I.; Stepushkina, V.V.; Tikhomirova, G.S.

    1985-01-01

    The dependences of Am, Cm, Bk, Cf and Es behavior on anion- and cation-exchangers in solutions of 0.1-8.0 M H/sub 3/PO/sub 4/ on acid concentration and oxidant content in solution (KBrO/sub 3/) or in resin (PbO/sub 2/) have been studied. Significant differences in distribution coefficients of Bk and other transplutonium elements (TPE) have been found that can be explained by Bk oxidation to the tetravalent state. A simple and effective method of Bk (IV) separation from trivalent TPE has been developed. The method was applied to the isolation of isotopes Bk-249 and Bk-250; the purification factor of Bk (IV) from other TPE is 10/sup 4/-10/sub 6/ per cycle. The possibility of Bk separation from bromate and phosphate ions by its sorption on a cation-exchanger from diluted H/sub 3/PO/sub 4/ solutions with subsequent desorption by the mineral acid has been shown. 20 references, 8 figures.

  8. BLT-EC (Breach, Leach Transport, and Equilibrium Chemistry), a finite-element model for assessing the release of radionuclides from low-level waste disposal units: Background, theory, and model description

    SciTech Connect

    MacKinnon, R.J.; Sullivan, T.M.; Simonson, S.A.; Suen, C.J.

    1995-08-01

    Performance assessment models typically account for the processes of sorption and dissolution-precipitation by using an empirical distribution coefficient, commonly referred to as K{sub d} that combines the effects of all chemical reactions between solid and aqueous phases. In recent years, however, there has been an increasing awareness that performance assessments based solely on empirically based K{sub d} models may be incomplete, particularly for applications involving radionuclides having sorption and solubility properties that are sensitive to variations in the in-situ chemical environment. To accommodate variations in the in-situ chemical environment, and to assess its impact on radionuclide mobility, it is necessary to model radionuclide release, transport, and chemical processes in a coupled fashion. This modeling has been done and incorporated into the two-dimensional, finite-element, computer code BLT-EC (Breach, Leach, Transport, Equilibrium Chemistry). BLT-EC is capable of predicting container degradation, waste-form leaching, and advective-dispersive, multispecies, solute transport. BLT-EC accounts for retardation directly by modeling the chemical processes of complexation, sorption, dissolution-precipitation, ion-exchange, and oxidation-reduction reactions. In this report we: (1) present a detailed description of the various physical and chemical processes that control the release and migration of radionuclides from shallow land LLW disposal facilities; (2) formulate the mathematical models that represent these processes; (3) outline how these models are incorporated and implemented in BLT-EC; and (4) demonstrate the application of BLT-EC on a set of example problems.

  9. Release of nickel ions from stainless steel alloys used in dental braces and their patch test reactivity in nickel-sensitive individuals.

    PubMed

    Jensen, Christian Stab; Lisby, Steen; Baadsgaard, Ole; Byrialsen, Kirsten; Menné, Torkil

    2003-06-01

    Nickel ions leached in sufficient quantities from nickel-containing alloys may induce nickel sensitization or elicit allergic contact dermatitis. Nickel-containing stainless steel alloys are generally considered safe for nickel-sensitive individuals to use. The study summarized in this paper investigated 3 parameters. First, the release of nickel was estimated in artificial saliva and sweat from 4 different stainless steel alloys frequently used in dental braces. Second, in a pilot study, oral mucosa cells harvested from 3 dental patients before and after the attachment of dental braces were analysed for possible nickel content. Third, patch test reactivity of the 4 stainless steel alloys was tested on 31 nickel-sensitive subjects. All 4 stainless steel alloys released small amounts of nickel ions into artificial saliva (<0.13 micro g/cm2/week) and artificial sweat (<0.05 micro g/cm2/week), but no measurable amounts of nickel were found in any of the oral mucosa samples. None of the 31 nickel-sensitive subjects reacted to patch testing with the 4 stainless steel alloys, indicating that these stainless steel alloys would be safe to use in direct and prolonged contact with the skin.

  10. Ion release and surface oxide composition of AISI 316L, Co-28Cr-6Mo, and Ti-6Al-4V alloys immersed in human serum albumin solutions.

    PubMed

    Karimi, Shima; Alfantazi, Akram M

    2014-07-01

    The long-term weight loss, ion release, and surface composition of 316L, Co-28Cr-6Mo and Ti-6Al-4V alloys were investigated in a simulated body environment. The samples were immersed in phosphate-buffered saline (PBS) solutions with various human serum albumin (HSA) concentrations for 8, 14, and 22 weeks. The specimens initially lost weight up to 14 weeks and then slightly gained weight. The analysis of the released ions was performed by induced coupled plasma-optical emission spectrometer (ICP-OES). The results revealed that the precipitation of the dissolved Fe and Co could cause the weight gain of the 316L and Co-28Cr-6Mo alloys. The surface chemistry of the specimens was determined by X-ray photoelectron spectroscopy (XPS). The XPS analysis of Co-28Cr-6Mo alloy showed that the interaction of Mo with HSA is different from Mo with bovine serum albumin (BSA). This was also observed for Na adsorption into the oxide layer of Ti-6Al-4V alloy in the presence of HSA and BSA.

  11. Involvement of Transducer of Regulated cAMP Response Element-Binding Protein Activity on Corticotropin Releasing Hormone Transcription

    PubMed Central

    Liu, Ying; Coello, Ana G.; Grinevich, Valery; Aguilera, Greti

    2010-01-01

    We have recently shown that phospho-cAMP response element-binding protein (CREB) is essential but not sufficient for activation of CRH transcription, suggesting the requirement of a coactivator. Here, we test the hypothesis that the CREB coactivator, transducer of regulated CREB activity (TORC), is required for activation of CRH transcription, using the cell line 4B and primary cultures of hypothalamic neurons. Immunohistochemistry and Western blot experiments in 4B cells revealed time-dependent nuclear translocation of TORC1,TORC 2, and TORC3 by forskolin [but not by the phorbol ester, phorbol 12-myristate 13-acetate (PMA)] in a concentration-dependent manner. In reporter gene assays, cotransfection of TORC1 or TORC2 potentiated the stimulatory effect of forskolin on CRH promoter activity but had no effect in cells treated with PMA. Knockout of endogenous TORC using silencing RNA markedly inhibited forskolin-activated CRH promoter activity in 4B cells, as well as the induction of endogenous CRH primary transcript by forskolin in primary neuronal cultures. Coimmunoprecipitation and chromatin immunoprecipitation experiments in 4B cells revealed association of CREB and TORC in the nucleus, and recruitment of TORC2 by the CRH promoter, after 20-min incubation with forskolin. These studies demonstrate a correlation between nuclear translocation of TORC with association to the CRH promoter and activation of CRH transcription. The data suggest that TORC is required for transcriptional activation of the CRH promoter by acting as a CREB coactivator. In addition, cytoplasmic retention of TORC during PMA treatment is likely to explain the failure of phorbolesters to activate CRH transcription in spite of efficiently phosphorylating CREB. PMID:20080871

  12. Electrical-thermal-structural finite element simulation and experimental study of a plasma ion source for the production of radioactive ion beams.

    PubMed

    Manzolaro, M; Meneghetti, G; Andrighetto, A; Vivian, G

    2016-03-01

    The production target and the ion source constitute the core of the selective production of exotic species (SPES) facility. In this complex experimental apparatus for the production of radioactive ion beams, a 40 MeV, 200 μA proton beam directly impinges a uranium carbide target, generating approximately 10(13) fissions per second. The transfer line enables the unstable isotopes generated by the (238)U fissions in the target to reach the ion source, where they can be ionized and finally accelerated to the subsequent areas of the facility. In this work, the plasma ion source currently adopted for the SPES facility is analyzed in detail by means of electrical, thermal, and structural numerical models. Next, theoretical results are compared with the electric potential difference, temperature, and displacement measurements. Experimental tests with stable ion beams are also presented and discussed.

  13. The pH-dependent release of platinum group elements (PGEs) from gasoline and diesel fuel catalysts: Implication for weathering in soils.

    PubMed

    Suchá, Veronika; Mihaljevič, Martin; Ettler, Vojtěch; Strnad, Ladislav

    2016-04-15

    Powdered samples of new and old gasoline catalysts (Pt, Pd, Rh) and new and old diesel (Pt) catalysts were subjected to a pH-static leaching procedure (pH 2-9) coupled with thermodynamic modeling using PHREEQC-3 to verify the release and mobility of PGEs (platinum group elements). PGEs were released under acidic conditions, mostly exhibiting L-shaped leaching patterns: diesel old: 5.47, 0.005, 0.02; diesel new: 68.5, 0.23, 0.11; gasoline old: 0.1, 11.8, 4.79; gasoline new 2.6, 25.2, 35.9 in mg kg(-1) for Pt, Pd and Rh, respectively. Only the new diesel catalyst had a strikingly different leaching pattern with elevated concentrations at pH 4, probably influenced by the dissolution of the catalyst carrier and washcoat. The pH-static experiment coupled with thermodynamic modeling was found to be an effective instrument for understanding the leaching behavior of PGEs under various environmental conditions, and indicated that charged Pt and Rh species may be adsorbed on the negatively charged surface of kaolinite or Mn oxides in the soil system, whereas uncharged Pd and Rh species may remain mobile in soil solutions.

  14. Corrosion-related changes on Ti-based orthodontic brackets in acetic NaF solutions: surface morphology, microhardness, and element release.

    PubMed

    Kang, Eun-Hee; Park, Soo-Byung; Kim, Hyung-Il; Kwon, Yong Hoon

    2008-07-01

    This study sought to investigate the effects of acetic NaF solutions on titanium and Ti alloy brackets. To this end, two different brackets were immersed in various NaF-containing solutions for three days. The Equilibrium Ti (EQ) bracket was composed of Ti only, whereas the Ortho 2 (OR) bracket was composed of Ti (base) and Ti-6A1-4V (wings). Brackets that were immersed in the acetic NaF solution of pH 3.5 yielded no reliable surface microhardness values due to corrosion. In other test solutions, however, there was minimal reduction (at best 3%) in microhardness. Further on microhardness, the values of the OR bracket at the base and wings were different. On the release of elements, it was significant only in the acetic NaF solution of pH 3.5. However, the release of Al (6.11+/-0.93 ppm) and V (1.16+/-0.40 ppm) in this solution was low. In conclusion, an acetic NaF solution of low pH could damage Ti-based orthodontic brackets.

  15. Effect of carbon on the microstructure, mechanical properties and metal ion release of Ni-free Co-Cr-Mo alloys containing nitrogen.

    PubMed

    Mori, Manami; Yamanaka, Kenta; Kuramoto, Koji; Ohmura, Kazuyo; Ashino, Tetsuya; Chiba, Akihiko

    2015-10-01

    This paper investigated the effect of carbon addition on the microstructure and tensile properties of Ni-free biomedical Co-29Cr-6Mo (mass%) alloys containing 0.2 mass% nitrogen. The release of metal ions by the alloys was preliminarily evaluated in an aqueous solution of 0.6% sodium chloride (NaCl) and 1% lactic acid, after which samples with different carbon contents were subjected to hot rolling. All specimens were found to primarily consist of a γ-phase matrix due to nitrogen doping, with only the volume fraction of M23C6 increasing with carbon concentration. Owing to the very fine size of these carbide particles (less than 1 μm), which results from fragmentation during hot rolling, the increased formation of M23C6 increased the 0.2% proof stress, but reduced the elongation-to-failure. Carbon addition also increased the amount of Co and Cr released during static immersion; Co and Cr concentrations at the surfaces, which increased with increasing the bulk carbon concentrations, possibly enhanced the metal ion release. However, only a very small change in the Mo concentration was noticed in the solution. Therefore, it is not necessarily considered a suitable means of improving the strength of biomedical Co-Cr-Mo alloys, even though it has only to date been used in this alloy system. The results of this study revealed the limitations of the carbon strengthening and can aid in the design of biomedical Co-Cr-Mo-based alloys that exhibit the high durability needed for their practical application.

  16. Selective extraction and release using (EDTA-Ni)-layered double hydroxide coupled with catalytic oxidation of 3,3',5,5'-tetramethylbenzidine for sensitive detection of copper ion.

    PubMed

    Tang, Sheng; Chang, Yuepeng; Chia, Guo Hui; Lee, Hian Kee

    2015-07-23

    Copper is an important heavy metal in various biological processes. Many methods have been developed for detecting of copper ions (Cu(2+)) in aqueous samples. However, an easy, cheap, selective and sensitive method is still desired. In this study, a selective extraction-release-catalysis approach has been developed for sensitive detection of copper ion. Ethylenediaminetetraacetic acid (EDTA) chelated with nickel ion (Ni(2+)) were intercalated in a layered double hydroxide via a co-precipitation reaction. The product was subsequently applied as sorbent in dispersive solid-phase extraction for the enrichment of Cu(2+) at pH 6. Since Cu(2+) has a stronger complex formation constant with EDTA, Ni(2+) exchanged with Cu(2+) selectively. The resulting sorbent containing Cu(2+) was transferred to catalyze the 3,3',5,5'-tetramethylbenzidine oxidation reaction, since Cu(2+) could be released by the sorbent effectively and has high catalytic ability for the reaction. Blue light emitted from the oxidation product was measured by ultraviolet-visible spectrophotometry for the determination of Cu(2+). The extraction temperature, extraction time, and catalysis time were optimized. The results showed that this method provided a low limit of detection of 10nM, a wide linear range (0.05-100μM) and good linearity (r(2)=0.9977). The optimized conditions were applied to environmental water samples. Using Cu(2+) as an example, this work provided a new and interesting approach for the convenient and efficient detection of metal cations in aqueous samples.

  17. Quantitation of fluoride ion released sarin in red blood cell samples by gas chromatography-chemical ionization mass spectrometry using isotope dilution and large-volume injection.

    PubMed

    Jakubowski, E M; McGuire, J M; Evans, R A; Edwards, J L; Hulet, S W; Benton, B J; Forster, J S; Burnett, D C; Muse, W T; Matson, K; Crouse, C L; Mioduszewski, R J; Thomson, S A

    2004-01-01

    A new method for measuring fluoride ion released isopropyl methylphosphonofluoridate (sarin, GB) in the red blood cell fraction was developed that utilizes an autoinjector, a large-volume injector port (LVI), positive ion ammonia chemical ionization detection in the SIM mode, and a deuterated stable isotope internal standard. This method was applied to red blood cell (RBC) and plasma ethyl acetate extracts from spiked human and animal whole blood samples and from whole blood of minipigs, guinea pigs, and rats exposed by whole-body sarin inhalation. Evidence of nerve agent exposure was detected in plasma and red blood cells at low levels of exposure. The linear method range of quantitation was 10-1000 pg on-column with a detection limit of approximately 2-pg on-column. In the course of method development, several conditions were optimized for the LVI, including type of injector insert, injection volume, initial temperature, pressure, and flow rate. RBC fractions had advantages over the plasma with respect to assessing nerve agent exposure using the fluoride ion method especially in samples with low serum butyrylcholinesterase activity.

  18. Potential curves and nonadiabatic matrix elements for collisions involving fragments of the HeN + molecular ion

    NASA Astrophysics Data System (ADS)

    Gu, Jian-ping; Buenker, Robert J.; Hirsch, Gerhard; Kimura, Mineo

    1995-05-01

    Ab initio multireference CI calculations have been carried out for the HeN+ molecular ion in order to describe collision processes between its constituent neutral and ionized atoms. The accuracy of these calculations is evaluated by means of a comparison of results obtained at large internuclear separations with the corresponding asymptotic energies deduced from atomic spectral data. Energy values are computed for the eleven lowest He++N and He+N+ atomic limits and average discrepancies relative to the experimental excitation energies up to 110 000 cm-1 are found to lie in the 1000-3000 cm-1 range, of which only 200 cm-1 appears to be the fault of the configuration interaction (CI) technique itself, with the main portion of the error stemming from the choice of atomic orbital (AO) basis instead. The HeN+ X 3Σ- ground state is calculated to have a De value of only 1414 cm-1, but the excited 2 3Π state has a much larger value of 22 133 cm-1 by virtue of an avoided crossing with the lower state of this symmetry. The corresponding radial nonadiabatic coupling is responsible for a large cross section for an excitation process between the N+(3Pg)+He and N+(3Du)+He channels which indirectly provides an efficient electron-capture mechanism leading to the N(4Su)+He+ exit channel. Additional nonadiabatic matrix elements for rotational and spin-orbit coupling have also been obtained and analyzed, as well as transition moments between the various HeN+ molecular states calculated.

  19. Controlled release of biologically active silver from nanosilver surfaces.

    PubMed

    Liu, Jingyu; Sonshine, David A; Shervani, Saira; Hurt, Robert H

    2010-11-23

    Major pathways in the antibacterial activity and eukaryotic toxicity of nanosilver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nanosilver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nanosilver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nanosilver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nanosilver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over 4 orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by preoxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and releasing inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through a bacterial inhibition zone assay carried out on selected formulations of controlled release nanosilver.

  20. Thermal-electric coupled-field finite element modeling and experimental testing of high-temperature ion sources for the production of radioactive ion beams

    SciTech Connect

    Manzolaro, M. Andrighetto, A.; Meneghetti, G.; Vivian, G.; D’Agostini, F.

    2016-02-15

    In isotope separation on line facilities the target system and the related ion source are two of the most critical components. In the context of the selective production of exotic species (SPES) project, a 40 MeV 200 μA proton beam directly impinges a uranium carbide target, generating approximately 10{sup 13} fissions per second. The radioactive isotopes produced in this way are then directed to the ion source, where they can be ionized and finally accelerated to the subsequent areas of the facility. In this work both the surface ion source and the plasma ion source adopted for the SPES facility are presented and studied by means of numerical thermal-electric models. Then, numerical results are compared with temperature and electric potential difference measurements, and finally the main advantages of the proposed simulation approach are discussed.

  1. Ion microprobe studies of trace elements in Apollo 14 volcanic glass beads - Comparisons to Apollo 14 mare basalts and petrogenesis of picritic magmas

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Papike, J. J.; Simon, S. B.; Shimizu, N.; Yurimoto, H.

    1990-01-01

    Results are presented from trace element analysis, by ion microprobe techniques, of individual glass beads representing seven compositionally distinct types of picritic glass beads from the Apollo 14 landing site. The picritic glass beads at the A-14 exhibited a wide range of primary magma compositions and a lack of petrogenetic linkage (via crystal fractionation) to crystalline basalts. The wide range of major and trace element characteristics of the picritic glass beads is consistent with derivation from mineralogically distinct sources which consist of varying proportions of olivine + orthopyroxene +/- clonopyroxene +/- ilmenite +/- plagioclase +/- KREEP component.

  2. Isolation and separation of transplutonium elements from other actinides on ion exchange resins from aqueous and aqueous ethanol solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1987-11-01

    The behavior of Am, Cm, Bk, Cf, Es, and other actinides, as well as Zr, on an anion exchange resin and a cation exchange resin in aqueous and aqueous alcohol solutions of sulfuric acid was investigated as a function of the concentration of various components of the solution. It was found that the presence of alcohol in sulfuric acid solutions leads to an increase in the distribution coefficients both on cation exchange resins and on anion exchange resins. The possibility of using ion exchange resins for the concentration and separation of transplutonium elements from U, Np, Pu, Zr, and other elements that form strong complexes with sulfate ions in a wide range of sulfuric acid concentrations was demonstrated.

  3. Toxic responses in rat embryonic cells to silver nanoparticles and released silver ions as analyzed via gene expression profiles and transmission electron microscopy.

    PubMed

    Xu, Liming; Shi, Chang; Shao, Anliang; Li, Xuefei; Cheng, Xiang; Ding, Rigao; Wu, Gang; Chou, Laisheng Lee

    2015-05-01

    After exposing rat embryonic cells to 20 μg/mL of silver nanoparticle (NP) suspension and their released ions for different time periods, silver nanoparticles were found in cellular nuclei, mitochondria, cytoplasm and lysosomes by transmission electron microscopy (TEM). We also observed mitochondrial destruction, distension of endoplasmic reticulum and apoptotic bodies. Global gene expression analysis showed a total of 279 genes that were up-regulated and 389 genes that were down-regulated in the silver-NP suspension exposure group, while 3 genes were up-regulated and 41 genes were down-regulated in the silver ion exposure group. Further, the GO pathway analysis suggested that these differentially expressed genes are involved in several biological processes, such as energy metabolism, oxygen transport, enzyme activities, molecular binding, etc. It is possible that inhibition of oxygen transport is mediated by the significant down-regulation of genes of the globin family, which might play an important role in silver ion-induced toxicity. KEGG pathway analysis showed that there were 23 signal pathways that were affected in the cells after exposure to silver-NP suspension, but not silver ion alone. The most significant change concerned inflammatory signal pathways, which were only found in silver-NP suspension exposed cells, indicating that inflammatory response might play an important role in the mechanism(s) of silver-NP-induced toxicity. The significant up-regulation of matrix metalloproteinases 3 and 9 suggests that silver NPs could induce extracellular matrix degradation via an inflammatory signaling pathway. The significant up-regulation of secretory leukocyte peptidase inhibitor and serine protease inhibitor 2c was considered to be an embryonic cellular defense mechanism in response to silver-NP-induced inflammation.

  4. Collision-induced release, ion mobility separation, and amino acid sequence analysis of subunits from mass-selected noncovalent protein complexes.

    PubMed

    Rathore, Deepali; Dodds, Eric D

    2014-09-01

    In recent years, mass spectrometry has become a valuable tool for detecting and characterizing protein-protein interactions and for measuring the masses and subunit stoichiometries of noncovalent protein complexes. The gas-phase dissociation of noncovalent protein assemblies via tandem mass spectrometry can be useful in confirming subunit masses and stoichiometries; however, dissociation experiments that are able to yield subunit sequence information must usually be conducted separately. Here, we furnish proof of concept for a method that allows subunit sequence information to be directly obtained from a protein aggregate in a single gas-phase analysis. The experiments were carried out using a quadrupole time-of-flight mass spectrometer equipped with a traveling-wave ion mobility separator. This instrument configuration allows for a noncovalent protein assembly to be quadrupole selected, then subjected to two successive rounds of collision-induced dissociation with an intervening stage of ion mobility separation. This approach was applied to four model proteins as their corresponding homodimers: glucagon, ubiquitin, cytochrome c, and β-lactoglobulin. In each case, b- and y-type fragment ions were obtained upon further collisional activation of the collisionally-released subunits, resulting in up to 50% sequence coverage. Owing to the incorporation of an ion mobility separation, these results also suggest the intriguing possibility of measuring complex mass, complex collisional cross section, subunit masses, subunit collisional cross sections, and sequence information for the subunits in a single gas-phase experiment. Overall, these findings represent a significant contribution towards the realization of protein interactomic analyses, which begin with native complexes and directly yield subunit identities.

  5. Collision-Induced Release, Ion Mobility Separation, and Amino Acid Sequence Analysis of Subunits from Mass-Selected Noncovalent Protein Complexes

    NASA Astrophysics Data System (ADS)

    Rathore, Deepali; Dodds, Eric D.

    2014-09-01

    In recent years, mass spectrometry has become a valuable tool for detecting and characterizing protein-protein interactions and for measuring the masses and subunit stoichiometries of noncovalent protein complexes. The gas-phase dissociation of noncovalent protein assemblies via tandem mass spectrometry can be useful in confirming subunit masses and stoichiometries; however, dissociation experiments that are able to yield subunit sequence information must usually be conducted separately. Here, we furnish proof of concept for a method that allows subunit sequence information to be directly obtained from a protein aggregate in a single gas-phase analysis. The experiments were carried out using a quadrupole time-of-flight mass spectrometer equipped with a traveling-wave ion mobility separator. This instrument configuration allows for a noncovalent protein assembly to be quadrupole selected, then subjected to two successive rounds of collision-induced dissociation with an intervening stage of ion mobility separation. This approach was applied to four model proteins as their corresponding homodimers: glucagon, ubiquitin, cytochrome c, and β-lactoglobulin. In each case, b- and y-type fragment ions were obtained upon further collisional activation of the collisionally-released subunits, resulting in up to 50% sequence coverage. Owing to the incorporation of an ion mobility separation, these results also suggest the intriguing possibility of measuring complex mass, complex collisional cross section, subunit masses, subunit collisional cross sections, and sequence information for the subunits in a single gas-phase experiment. Overall, these findings represent a significant contribution towards the realization of protein interactomic analyses, which begin with native complexes and directly yield subunit identities.

  6. Coumarin-modified microporous-mesoporous Zn-MOF-74 showing ultra-high uptake capacity and photo-switched storage/release of U(VI) ions.

    PubMed

    Zhang, Le; Wang, Lin Lin; Gong, Le Le; Feng, Xue Feng; Luo, Ming Biao; Luo, Feng

    2016-07-05

    Driven by an energy crisis but consequently puzzled by various environmental problems, uranium, as the basic material of nuclear energy, is now receiving extensive attentions. In contrast to numerous sorbents applied in this field, metal-organic framework (MOFs), as a renovated material platform, has only recently been developed. How to improve the adsorption capacity of MOF materials towards U(VI) ions, as well as taking advantage of the nature of these MOFs to design photo-switched behaviour for photo-triggered storage/release of U(VI) ions are at present urgent problems and great challenges to be solved. Herein, we show a simple and facile method to target the goal. Through coordination-based post-synthetic strategy, microporous- mesoporous Zn-MOF-74 was easily functionalized by grafting coumarin on coordinatively unsaturated Zn(II) centers, yielding a series of coumarin-modified Zn-MOF-74 materials. The obtained samples displayed ultra-high adsorption capacity for U(VI) ions from water at pH value of 4 with maximum adsorption capacities as high as 360 mg/g (the record value in MOFs) and a remarkable photo-switched capability of 50 mg/g at pH value of 4. To the best of knowledge, and in contrast to the well-known photo-switched behaviour towards CO2, dye (propidium iodide), as well as fluorescence observed in MOFs, this is the first study that shows a photo-switched behaviour towards radioactive U(VI) ions in aqueous solution.

  7. Trace element incorporation into quartz: A combined study by ICP-MS, electron spin resonance, cathodoluminescence, capillary ion analysis, and gas chromatography

    NASA Astrophysics Data System (ADS)

    Götze, Jens; Plötze, Michael; Graupner, Torsten; Hallbauer, Dieter Klaus; Bray, Colin J.

    2004-09-01

    Pegmatite quartz from different occurrences in Norway and Namibia was investigated by a combination of ICP-MS, Electron Spin Resonance (ESR), Capillary Ion Analysis (CIA) and Gas Chromatography (GC) to quantify trace elements in very low concentrations and to determine their position in the quartz structure. The studied quartz samples show similar geochemical characteristics with low contents of most trace elements. Remarkable are the elevated concentrations of Al (36-636 ppm), Ti (1.6-25.2 ppm), Ge (1.0-7.1 ppm), Na (5.2 to >50 ppm), K (1.6 to >100 ppm) and Li (2.1-165.6 ppm). These elements are preferentially incorporated into the quartz lattice on substitutional (Al, Ti, Ge) and interstitial (Li, Na, K) positions. Li + was found to be the main charge compensating ion for Al, Ge and Ti, whereas some ppm of Na and K may also be hosted by fluid inclusions. Ti may be incorporated as substitutional ion for Si or bound on mineral microinclusions (rutile). The results of the ESR measurements show that there may be a redistribution of alkali ions during irradiation. The diamagnetic [AlO 4/M +] 0 center transforms into the paramagnetic [AlO 4] 0 center, whilst the compensating ions diffuse away and may be captured by the diamagnetic precursor centers of [GeO 4] 0 and [TiO 4] 0 to form paramagnetic centers ([TiO 4/Li +] 0, [GeO 4/Li +] 0). In general, fluid inclusions in pegmatite quartz can be classified as H 2O-CO 2-NaCl type inclusions with water as the predominant volatile. Among the main elements hosted by fluid inclusions in quartz are Na, K, NH 4, Ca, Mg and the anionic complexes Cl -, NO 3-, HCO 3- and SO 42-. Gas analysis of trapped fluids shows volatile components in the following order of abundance: H 2O > CO 2 > N 2(+) ≥ CH 4 > COS > C 2 and C 3 hydrocarbons. Additionally, traces of Co, Ni, Zn, Pb, and Cu were detected by CIA in fluid inclusions of some samples. There are indications that the REE and Rb are also bound in fluid inclusions, however, the

  8. Principal locations of major-ion, trace-element, nitrate, and Escherichia coli loading to Emigration Creek, Salt Lake County, Utah, October 2005

    USGS Publications Warehouse

    Kimball, Briant A.; Runkel, Robert L.; Walton-Day, Katherine

    2008-01-01

    Housing development and recreational activity in Emigration Canyon have increased substantially since 1980, perhaps causing an observed decrease in water quality of this northern Utah stream located near Salt Lake City. To identify reaches of the stream that contribute to water-quality degradation, a tracer-injection and synoptic-sampling study was done to quantify mass loading of major ions, trace elements, nitrate, and Escherichia coli (E. coli) to the stream. The resulting mass-loading profiles for major ions and trace elements indicate both geologic and anthropogenic inputs to the stream, principally from tributary and spring inflows to the stream at Brigham Fork, Burr Fork, Wagner Spring, Emigration Tunnel Spring, Blacksmith Hollow, and Killyon Canyon. The pattern of nitrate loading does not correspond to the major-ion and trace-element loading patterns. Nitrate levels in the stream did not exceed water-quality standards at the time of synoptic sampling. The majority of nitrate mass loading can be considered related to anthropogenic input, based on the field settings and trends in stable isotope ratios of nitrogen. The pattern of E. coli loading does not correspond to the major-ion, trace-element, or nitrate loading patterns. The majority of E. coli loading was related to anthropogenic sources based on field setting, but a considerable part of the loading also comes from possible animal sources in Killyon Canyon, in Perkins Flat, and in Rotary Park. In this late summer sampling, E. coli concentrations only exceeded water-quality standards in limited sections of the study reach. The mass-loading approach used in this study provides a means to design future studies and to evaluate the loading on a catchment scale.

  9. The effect of calcium ions on the binomial statistic parameters that control acetylcholine release at preganglionic nerve terminals.

    PubMed Central

    Bennett, M R; Florin, T; Pettigrew, A G

    1976-01-01

    1. A study has been made of the effects of changing [Ca]O and [Mg]O on the binomial statistic parameters p and n that control the average quantal content (m) of the excitatory post-synaptic potential (e.p.s.p.) due to acetylcholine release at preganglionic nerve terminals. 2. When [Ca]O was increased in the range from 0-2 to 0-5 mM, p increased as the first power of [Ca]O whereas n increased as the 0-5 power of [Ca]O; when [Mg]O was increased in the range from 5 to 200 mM, p decreased as the first power of [Mg]O whereas n decreased as the 0-5 power of [Mg]O. 3. The increase in quantal release of a test impulse following a conditioning impulse was primarily due to an increase in n; the increase in quantal content of successive e.p.s.p.s in a short train was due to an increase in n and p, and the increase in n was quantitatively described in terms of the accumulation of a Ca-receptor complex in the nerve terminal. 4. The decrease in quantal content of successive e.p.s.p.s during long trains of impulses over several minutes was primarily due to a decrease in n. These results are discussed in terms of an hypothesis concerning the physical basis of n and p in the release process. PMID:181562

  10. Structure of a prokaryotic sodium channel pore reveals essential gating elements and an outer ion binding site common to eukaryotic channels.

    PubMed

    Shaya, David; Findeisen, Felix; Abderemane-Ali, Fayal; Arrigoni, Cristina; Wong, Stephanie; Nurva, Shailika Reddy; Loussouarn, Gildas; Minor, Daniel L

    2014-01-23

    Voltage-gated sodium channels (NaVs) are central elements of cellular excitation. Notwithstanding advances from recent bacterial NaV (BacNaV) structures, key questions about gating and ion selectivity remain. Here, we present a closed conformation of NaVAe1p, a pore-only BacNaV derived from NaVAe1, a BacNaV from the arsenite oxidizer Alkalilimnicola ehrlichei found in Mono Lake, California, that provides insight into both fundamental properties. The structure reveals a pore domain in which the pore-lining S6 helix connects to a helical cytoplasmic tail. Electrophysiological studies of full-length BacNaVs show that two elements defined by the NaVAe1p structure, an S6 activation gate position and the cytoplasmic tail "neck", are central to BacNaV gating. The structure also reveals the selectivity filter ion entry site, termed the "outer ion" site. Comparison with mammalian voltage-gated calcium channel (CaV) selectivity filters, together with functional studies, shows that this site forms a previously unknown determinant of CaV high-affinity calcium binding. Our findings underscore commonalities between BacNaVs and eukaryotic voltage-gated channels and provide a framework for understanding gating and ion permeation in this superfamily.

  11. Multireference - Møller-Plesset Perturbation Theory Results on Levels and Transition Rates in Al-like Ions of Iron Group Elements

    SciTech Connect

    Santana, J A; Ishikawa, Y; Tr�abert, E

    2009-02-26

    Ground configuration and low-lying levels of Al-like ions contribute to a variety of laboratory and solar spectra, but the available information in databases are neither complete not necessarily correct. We have performed multireference Moeller-Plesset perturbation theory calculations that approach spectroscopic accuracy in order to check the information that databases hold on the 40 lowest levels of Al-Like ions of iron group elements (K through Ge), and to provide input for the interpretation of concurrent experiments. Our results indicate problems of the database holdings on the levels of the lowest quartet levels in the lighter elements of the range studied. The results of our calculations of the decay rates of five long-lived levels (3s{sup 2}3p {sup 2}p{sup o}{sub 3/2}, 3s3p{sup 2} {sup 4}P{sup o} J and 3s3p3d {sup 4}F{sup o}{sub 9/2}) are compared with lifetime data from beam-foil, electron beam ion trap and heavy-ion storage ring experiments.

  12. Release of somatostatin-like immunoreactivity from the perfused canine thyroid. Selective stimulatory effect of calcium ions.

    PubMed

    Laurberg, P; Orskov, H

    1981-05-01

    It is well accepted that the C cells of the thyroid contain somatostatin, but the role in local endocrine function has not yet been firmly established in this organ, and it has not been proved that thyroidal somatostatin is released into the circulation. We have measured the contents of somatostatin-like immunoreactivity in the effluent of canine thyroid glands perfused without recirculation with a synthetic buffer medium. During basal conditions a definite release was consistently found in the order of 10 pg/ml corresponding to 12 pg/min. The somatostatin-like immunoreactivity was studied in dilution experiments and by gel-filtration chromatography, and found to have properties identical to those of synthetic cyclic somatostatin, which was also recovered quantitatively when added to sampling tubes. Various compounds were infused in concentrations that are highly active in pancreas perfusion experiments. 14-min infusion of arginine, 5 and 11.5 mmol/liter; isoproterenol, 10 and 23.7 nmol/liter and 68.7 mumol/liter; acetylcholine, 5 mumol/liter, carbamylcholine, 10 and 100 mumol/liter; glucagon, 1 and 30 nmol/liter; and porcine calcitonin, 1 and 100 ng/ml did not affect the basal release of somatostatin-like immunoreactivity significantly. Neither did an increase from the control level of 4 mmol/liter glucose of 10 or 20 mmol/liter, nor an increase in the control level of 4.4 mmol/liter K+ to 7.5 or 14.4 mmol/liter. Each of these compounds were tested in three or four dogs. The effect of an increase in Ca++ from the control level of 1.5 mmol/liter to 2.25, 3.0, and 4.5 mmol/liter was tested in random order in five thyroid lobes. All three doses elicited an immediate increase in effluent somatostatin-like immunoreactivity. In most experiments the response was biphasic with an early spike, followed by a stable level that was maintained during prolonged Ca++ infusion. The secretory response was not diminished through a series of repeated short pulses of calcium infusion

  13. Simultaneous depth-profiling of electrical and elemental properties of ion-implanted arsenic in silicon by combining secondary-ion mass spectrometry with resistivity measurements

    NASA Astrophysics Data System (ADS)

    Bennett, N. S.; Wong, C. S.; McNally, P. J.

    2016-07-01

    A method is proposed to extract the electrical data for surface doping profiles of semiconductors in unison with the chemical profile acquired by secondary-ion mass spectrometry (SIMS)—a method we call SIMSAR (secondary-ion mass spectrometry and resistivity). The SIMSAR approach utilizes the inherent sputtering process of SIMS, combined with sequential four-point van der Pauw resistivity measurements, to surmise the active doping profile as a function of depth. The technique is demonstrated for the case of ion-implanted arsenic doping profiles in silicon. Complications of the method are identified, explained, and corrections for these are given. While several techniques already exist for chemical dopant profiling and numerous for electrical profiling, since there is no technique which can measure both electrical and chemical profiles in parallel, SIMSAR has significant promise as an extension of the conventional dynamic SIMS technique, particularly for applications in the semiconductor industry.

  14. Simultaneous depth-profiling of electrical and elemental properties of ion-implanted arsenic in silicon by combining secondary-ion mass spectrometry with resistivity measurements.

    PubMed

    Bennett, N S; Wong, C S; McNally, P J

    2016-07-01

    A method is proposed to extract the electrical data for surface doping profiles of semiconductors in unison with the chemical profile acquired by secondary-ion mass spectrometry (SIMS)-a method we call SIMSAR (secondary-ion mass spectrometry and resistivity). The SIMSAR approach utilizes the inherent sputtering process of SIMS, combined with sequential four-point van der Pauw resistivity measurements, to surmise the active doping profile as a function of depth. The technique is demonstrated for the case of ion-implanted arsenic doping profiles in silicon. Complications of the method are identified, explained, and corrections for these are given. While several techniques already exist for chemical dopant profiling and numerous for electrical profiling, since there is no technique which can measure both electrical and chemical profiles in parallel, SIMSAR has significant promise as an extension of the conventional dynamic SIMS technique, particularly for applications in the semiconductor industry.

  15. Major ions, nutrients, and trace elements in the Mississippi River near Thebes, Illinois, July through September 1993

    USGS Publications Warehouse

    Taylor, Howard E.; Antweiler, Ronald C.; Brinton, Terry I.; Roth, David A.; Moody, John A.

    1994-01-01

    Extensive flooding in the upper Mississippi River Basin during summer 1993 had a significant effect on the water quality of the Mississippi River. To evaluate the change in temporal distribution and transport of dissolved constituents in the Mississippi River, six water samples were collected by a discharge-weighted method from July through September 1993 near Thebes, Illinois. Sampling at this location provided water-quality information from the upper Mississippi, the Missouri, and the Illinois River Basins. Dissolved major constituents that were analyzed in each of the samples included bicarbonate, calcium (Ca), carbonate (CO3), chloride (C1), dissolved organic carbon, magnesium (Mg), potassium (K), silica (SiO2) , sodium (Na), and sulfate (SO4). Dissolved nutrients included ammonium ion (NH4), nitrate (NO3), nitrite (NO2), and orthophosphate (PO4). Dissolved trace elements included aluminum (A1), arsenic (As), barium (Ba), boron (B), beryllium (Be), bromide (Br), cadmium (Cd), chromium (Cr), cobalt, (Co), copper (Cu), fluoride (F), iron (Fe), lead, lithium (Li), manganese (Mn), mercury (Hg), molybdenum (Mo), nickel (Ni), strontium (Sr), thallium, uranium (U), vanadium (V), and zinc (Zn). Other physical properties of water that were measured included specific conductance, pH and suspended-sediment concentration (particle size, less than 63 micrometers). Results of this study indicated that large quantifies of dissolved constituents were transported through the river system. Generally, pH, alkalinity, and specific conductance and the concentrations of B, Br, Ca, C1, Cr, K, Li, Mg, Mo, Na, SO4, Sr, U, and V increased as water discharge decreased, while concentrations of F, Hg, and suspended sediment sharply decreased as water discharge decreased after the crest of the flood. Concentrations of other constituents, such as A1, As, Ba, Be, Co, Cu, Ni, NO3, NO2, NH4, PO 4, and SiO2, varied with time as discharge decreased after the crest of the flood. For most

  16. Differentiation of Spores of Bacillus Subtilis Grown in Different Media by Elemental Characterization using Time-of-Flight Secondary Ion Mass Spectrometry

    SciTech Connect

    Cliff, John B.; Jarman, Kristin H.; Valentine, Nancy B.; Golledge, Stephen; Gaspar, Dan J.; Wunschel, David S.; Wahl, Karen L.

    2005-11-01

    We demonstrate the use of time of flight secondary ion mass spectrometry (ToF-SIMS) to infer the medium in which Bacillus subtilis spores were grown based on elemental signatures of the spores. Triplicate culture replicates grown in each of four different media were analyzed to obtain ToF-SIMS signatures comprised of 16 elemental intensities. The signatures were analyzed using ANOVA and principal components analysis (PCA). Confusion matrices constructed using nearest neighbor classification of the PCA scores confirmed the predictive utility of ToF-SIMS elemental signatures in identifying sporulation media. Application of this method will be of use in microbial forensics, and may also prove useful in the areas of food microbiology and astrobiology.

  17. An ion microprobe study of the intra-crystalline behavior of REE and selected trace elements in pyroxene from mare basalts with different cooling and crystallization histories

    NASA Technical Reports Server (NTRS)

    Shearer, C. K.; Papike, J. J.; Simon, S. B.; Shimizu, N.

    1989-01-01

    The effects of crystallization interaction on the trace element zoning characteristics of pyroxenes are analyzed using electron and ion microprobe techniques. Four pigeonite basalts with similar isochemical composition, but different cooling rates and crystallization histories are studied. Pyroxene quadrilaterals displaying crystallization trends are presented. The crystal chemical rationalization of REE zoning, pattern shapes, and abundances are examined. The data reveal that the trace element zoning characteristics in pyroxene and the partitioning of trace elements between pyroxene and the melt are related to the interaction between the efficiency of the crystallization process, the kinetics at the crystal-melt interface, the kinetics of plagioclase nucleation and the characteristics of the crystal chemical substitutions in the pyroxene and the associated crystallizing phase.

  18. Separation and preconcentration of the rare-earth elements and yttrium from geological materials by ion-exchange and sequential acid elution

    USGS Publications Warehouse

    Crock, J.G.; Lichte, F.E.; Riddle, G.O.; Beech, C.L.

    1986-01-01

    The abundance of rare-earth elements (REE) and yttrium in geological materials is generally low, and most samples contain elements that interfere in the determination of the REE and Y, so a separation and/or preconcentration step is often necessary. This is often achieved by ion-exchange chromatography with either nitric or hydrochloric acid. It is advantageous, however, to use both acids sequentially. The final solution thus obtained contains only the REE and Y, with minor amounts of Al, Ba, Ca, Sc, Sr and Ti. Elements that potentially interfere, such as Be, Co, Cr, Fe, Mn, Th, U, V and Zr, are virtually eliminated. Inductively-coupled argon plasma atomic-emission spectroscopy can then be used for a final precise and accurate measurement. The method can also be used with other instrumental methods of analysis. ?? 1986.

  19. Aminated polyethersulfone-silver nanoparticles (AgNPs-APES) composite membranes with controlled silver ion release for antibacterial and water treatment applications.

    PubMed

    Haider, M Salman; Shao, Godlisten N; Imran, S M; Park, Sung Soo; Abbas, Nadir; Tahir, M Suleman; Hussain, Manwar; Bae, Wookeun; Kim, Hee Taik

    2016-05-01

    The present study reports the antibacterial disinfection properties of a series of silver nanoparticle (AgNP) immobilized membranes. Initially, polyethersulfone (PES) was functionalized through the introduction of amino groups to form aminated polyethersulfone (NH2-PES, APES). AgNPs were then coordinately immobilized on the surface of the APES composite membrane to form AgNPs-APES. The properties of the obtained membrane were examined by FT-IR, XPS, XRD, TGA, ICP-OES and SEM-EDAX analyses. These structural characterizations revealed that AgNPs ranging from 5 to 40 nm were immobilized on the surface of the polymer membrane. Antibacterial tests of the samples showed that the AgNPs-APES exhibited higher activity than the AgNPs-PES un-functionalized membrane. Generally, the AgNPs-APES 1 cm × 3 cm strip revealed a four times longer life than the un-functionalized AgNPs polymer membranes. The evaluation of the Ag(+) leaching properties of the obtained samples indicated that approximately 30% of the AgNPs could be retained, even after 12 days of operation. Further analysis indicated that silver ion release can be sustained for approximately 25 days. The present study provides a systematic and novel approach to synthesize water treatment membranes with controlled and improved silver (Ag(+)) release to enhance the lifetime of the membranes.

  20. Comparison of ion-activated in situ gelling systems for ocular drug delivery. Part 1: physicochemical characterisation and in vitro release.

    PubMed

    Rupenthal, Ilva D; Green, Colin R; Alany, Raid G

    2011-06-15

    Conventional eye drops can result in poor drug bioavailability due to the unique ocular anatomy and physiology. Ion-activated in situ gelling systems are able to crosslink with cations present in the tear fluid, therefore forming a gel on the ocular surface, which results in prolonged corneal contact time. The present study compared a number of anionic polysaccharides (gellan gum, xanthan gum, carrageenan and alginate) to an uncharged (HPMC) and a positively charged (chitosan) polymer system with emphasis on the gelling behaviour, rheological and textural properties, gel microstructure, contact angle and in vitro release characteristics. All systems exhibited physically entangled polymer networks that were able to disentangle upon shear stress and significantly prolonged the in vitro release of a model hydrophilic drug compared to a solution. While systems based on HPMC and chitosan showed no structural changes upon addition of cations, formulations based on gellan gum and carrageenan demonstrated a remarkable increase in viscosity, pseudoplasticity and hardness upon addition of Ca(2+) and K(+) respectively. This renders them favourable for ocular use as they would gel once in contact with the cations of the tear fluid, thus reducing nasolacrimal drainage, but would thin upon shearing, preventing ocular irritation and therefore induced lacrimation.

  1. A Temperature-Responsive Smart Europium Metal-Organic Framework Switch for Reversible Capture and Release of Intrinsic Eu(3+) Ions.

    PubMed

    Zhu, Min; Song, Xue-Zhi; Song, Shu-Yan; Zhao, Shu-Na; Meng, Xing; Wu, Lan-Lan; Wang, Cheng; Zhang, Hong-Jie

    2015-04-01

    Stimuli-responsive structural transformations are emerging as a scaffold to develop a charming class of smart materials. A EuL metal-organic framework (MOF) undergoes a reversible temperature-stimulated single-crystal to single-crystal transformation, showing a specific behavior of fast capture/release of free Eu(3+) in the channels at low and room temperatures. At room temperature, compound 1a is obtained with one free carboxylate group severing as further hook, featuring one-dimensional square channels filled with intrinsic free europium ions. Trigged by lowering the ambient temperature, 1b is gained. In 1b, the intrinsic free europium ions can be fast captured by the carboxylate-hooks anchored in the framework, resulting in the structural change and its channel distortion. To the best of our knowledge, this is the first report of such a rapid and reversible switch stemming from dynamic control between noncovalent and covalent Eu-ligand interactions. Utilizing EuL MOF to detect highly explosive 2,4,6-trinitrophenol at room temperature and low temperature provides a glimpse into the potential of this material in fluorescence sensors.

  2. Tests on the extracted current density of negative hydrogen ions from a single element of the matrix source

    SciTech Connect

    Lishev, St.; Yordanov, D. Shivarova, A.

    2015-04-08

    Concepts for the extraction of volume-produced negative hydrogen ions from a rf matrix source (a matrix of small-radius discharges with a planar-coil inductive driving) are presented and discussed based on experimental results for the current densities of the extracted ions and the co-extracted electrons. The experiment has been carried out in a single discharge of the source: a rf discharge with a radius of 2.25 cm inductively driven by a 3.5-turn planar coil. The length of the discharge tube, the area of the reference electrode inserted in the discharge volume, the discharge modes, the magnetic filter and its position along the discharge length, the position of the permanent magnets for the separation of the co-extracted electrons from the extracted ions in the extraction device and the bias applied to its first electrode are considered as factors influencing the extracted currents of negative ions.

  3. Mineralogical and geochemical controls on the release of trace elements from slag produced by base- and precious-metal smelting at abandoned mine sites

    USGS Publications Warehouse

    Piatak, N.M.; Seal, R.R.; Hammarstrom, J.M.

    2004-01-01

    Slag collected from smelter sites associated with historic base-metal mines contains elevated concentrations of trace elements such as Cu, Zn and Pb. Weathering of slag piles, many of which were deposited along stream banks, potentially may release these trace elements into the environment. Slags were sampled from the Ely and Elizabeth mines in the Vermont copper belt, from the copper Basin mining district at Ducktown, Tennessee and from the Clayton silver mine in the Bayhorse mining district, Idaho, in the USA. Primary phases in the slags include: olivine-group minerals, glass, spinels, sulfide minerals and native metals for Vermont samples; glass, sulfide minerals and native metals for the Ducktown sample; and olivine-group minerals, clinopyroxenes, spinels, sulfide minerals, native metals and other unidentified metallic compounds for Clayton slag. Olivine-group minerals and pyroxenes are dominantly fayalitic and hedenbergitic in composition, respectively and contain up to 1.25 wt.% ZnO. Spinel minerals range between magnetite and hercynite in composition and contain Zn (up to 2.07 wt.% ZnO), Ti (up to 4.25 wt.% TiO2) and Cr (up to 1.39 wt.% Cr2O3). Cobalt, Ni, Cu, As, Ag, Sb and Pb occur in the glass phase, sulfides, metallic phases and unidentified metallic compounds. Bulk slag trace-element chemistry shows that the metals of the Vermont and Tennessee slags are dominated by Cu (1900-13,500 mg/kg) and Zn (2310-10,200 mg/kg), whereas the Clayton slag is dominated by Pb (63,000 mg/kg), Zn (19,700 mg/kg), Cu (7550 mg/kg), As (555 mg/kg), Sn (363 mg/kg) and Ag (200 mg/kg). Laboratory-based leach tests indicate metals can be released under simulated natural conditions. Leachates from most slags were found to contain elevated concentrations of Cu and Zn (up to 1800 and 470 ??g/l, respectively), well in excess of the acute toxicity guidelines for aquatic life. For the Idaho slag, the concentration of Pb in the leachate (11,000 ??g/l) is also in excess of the acute

  4. Heterozygous gsp mutation renders ion channels of human somatotroph adenoma cells unresponsive to growth hormone-releasing hormone.

    PubMed

    Yasufuku-Takano, J; Takano, K; Takei, T; Fukumoto, S; Teramoto, A; Takakura, K; Yamashita, N; Fujita, T

    1999-05-01

    Ionic mechanisms play an important role in the regulation of hormone secretion. The GHRH-induced GH release by human GH-secreting cells is transmitted through protein kinase A (PKA), which activates nonselective cation current (NSCC) and induces membrane depolarization, intracellular Ca2+ increase, and GH secretion. To evaluate whether ionic mechanisms have pathophysiological significance in GH oversecretion of GH-secreting pituitary adenomas, we examined four adenomas with constitutively active Gs alpha mutation (gsp mutation) and compared with three gsp-negative adenomas. In primary-cultured cells of gsp-positive adenomas, GHRH did not increase the NSCC under voltage-clamp experiments. Detailed examination showed that NSCC was maximally activated at the basal level and application of GHRH did not increase the current in these adenomas. Furthermore, by using single-cell RT-PCR method, we demonstrated for the first time at the single cell level that gsp mutation is heterozygous in GH-secreting pituitary adenomas. These indicate that heterozygous gsp mutation fully activates NSCC at the basal level, which may account for the GH oversecretion in gsp-positive GH-secreting pituitary adenomas.

  5. Structure of a prokaryotic sodium channel pore reveals essential gating elements and an outer ion binding site common to eukaryotic channels

    PubMed Central

    Shaya, David; Findeisen, Felix; Abderemane-Ali, Fayal; Arrigoni, Cristina; Wong, Stephanie; Nurva, Shailika Reddy; Loussouarn, Gildas; Minor, Daniel L.

    2013-01-01

    Voltage-gated sodium channels (NaVs) are central elements of cellular excitation. Notwithstanding advances from recent bacterial NaV (BacNaV) structures, key questions about gating and ion selectivity remain. Here, we present a closed conformation of NaVAe1p, a pore-only BacNaV derived from NaVAe1, a BacNaV from the arsenite oxidizer Alkalilimnicola ehrlichei found in Mono Lake, California, that provides insight into both fundamental properties. The structure reveals a pore domain in which the pore-lining S6 helix connects to a helical cytoplasmic tail. Electrophysiological studies of full-length BacNaVs show that two elements defined by the NaVAe1p structure, an S6 activation gate position and the cytoplasmic tail ‘neck’, are central to BacNaV gating. The structure also reveals the selectivity filter ion entry site, termed the ‘outer ion’ site. Comparison with mammalian voltage-gated calcium channel (CaV) selectivity filters, together with functional studies shows that this site forms a previously unknown determinant of CaV high affinity calcium binding. Our findings underscore commonalities between BacNaVs and eukaryotic voltage-gated channels and provide a framework for understanding gating and ion permeation in this superfamily. PMID:24120938

  6. Effects of crystallographic plane and co-deposited element on the growth of ion-sputter induced Si nano-cone arrays: a mechanism study

    NASA Astrophysics Data System (ADS)

    Song, Sheng-Chi; Qiu, Ying; Hao, Hong-Chen; Lu, Ming

    2015-06-01

    Self-organized Si nano-cone arrays induced by Ar+ ion sputtering on different Si crystallographic planes with different co-deposited alien atoms are investigated. The Si planes are (100), (110), and (111) ones, and the alien elements are Ta, Mo, Fe, and C, respectively. It is found that the growth of Si nano-cone arrays is insensitive to the initial crystallographic plane, but depends strongly on the co-deposited element. For the same Ar+ ion dose and sample temperature, the smaller the activation energy between the co-deposited element and Si is, the larger the average cone height and base diameter are. It is found that the preferential sputtering does not play an important role in the nano-cone formation. A model based on the concepts of classical surface-curvature-dependent sputtering yield and the formation of stationary silicide is proposed, which explains the observed results. The results of microstructural and compositional analysis support the proposed model.

  7. Effects of europium ions (Eu3+) on the distribution and related biological activities of elements in Lathyrus sativus L roots.

    PubMed

    Tian, Hong Er; Gao, Yong Sheng; Li, Feng Min; Zeng, Fuli

    2003-01-01

    Scanning electron microscopic and energy-dispersive X-ray analyses were used to study the distributions of different types of elements in the epidermis, exodermis, endodermis, and vascular cylinder of the fracture face in the Lathyrus sativus L. roots in the presence or absence of Eu3+. Some index of the biological activity related to the elements binding with protein were determined also. The results showed that the tissular distributions of elements in the fracture face are different in the presence and absence of Eu3+. The atomic percentages of P, S, Ca, and Mn were influenced more than those of other elements. Eu3+ promoted the biological activities of various kinds of element. The one possible mechanism changing the biological activities was that the reaction of Eu3+ +e--> Eu2+ would influence the electron capture or transport in elements of binding protein. Another mechanism was that CaM-Ca2+ becoming CaM-Eu3+ through Eu3+ instead of Ca2+ would affect the biological activity of elements by regulating the Ca2+ level in the plant cell.

  8. Ion irradiation induced element-enriched and depleted nanostructures in Zr-Al-Cu-Ni metallic glass

    SciTech Connect

    Chen, H. C.; Liu, R. D.; Yan, L. E-mail: zhouxingtai@sinap.ac.cn; Zhou, X. T. E-mail: zhouxingtai@sinap.ac.cn; Cao, G. Q.; Wang, G.

    2015-07-21

    The microstructural evolution of a Zr-Al-Cu-Ni metallic glass induced by irradiation with Ar ions was investigated. Under ion irradiation, the Cu- and Ni-enriched nanostructures (diameter of 30–50 nm) consisted of crystalline and amorphous structures were formed. Further, Cu- and Ni-depleted nanostructures with diameters of 5–20 nm were also observed. The formation of these nanostructures can be ascribed to the migration of Cu and Ni atoms in the irradiated metallic glass.

  9. Disturbances in cellular features and elemental homeostasis in the integument of a freshwater fish Channa punctatus (Bloch) in relation to hydrogen ion concentration of polluted water.

    PubMed

    Dey, S; Ramanujam, S N; Dkhar, R S; Bhattacharjee, C R; Purkayastha, D

    2001-01-01

    Scanning electron microscopy revealed that the cellular and morphological defects in the integument of Channa punctatus, associated with heavy metal and other environmental pollution was related to a significant extent to the hydrogen ion concentration of the water. At low pH, the epidermis showed severe lesions, and the scale lost its attachment with the skin, due to lepidontal alterations of the circuli. Atomic absorption spectroscopic analysis of the tissue indicated disturbances in the homeostasis of several elements, which probably played a major role in causing the cellular and morphological defects. Experimental monitoring of the pH of the polluted water to near-neutral, reduced significantly the extent of cellular and morphological defects and disturbances in elemental homeostasis.

  10. Partitioning of Large-ion Lithophile Elements Between Aqueous Fluids and Melts: Role of Saline Fluids in Sub-arc Mantle

    NASA Astrophysics Data System (ADS)

    Kawamoto, T.; Mibe, K.

    2014-12-01

    Chemical fractionation of slab-derived supercritical fluids can play an important role in elemental transfer from subducting slab to the mantle wedge and arc magmatism [1]. Recent findings of saline fluids from sub-arc mantle peridotite indicate that aqueous fluids in mantle wedge can contain 3.7 wt% NaCl in Ichinomageta, Northeast Japan arc [2] to 5.1 wt% NaCl in Pinatubo, Luzon arc [3]. It is, therefore, important to determine the effect of Cl on the trace element partitioning between aqueous fluids and melts. Synchrotron radiation X-ray fluorescence (XRF) analysis is conducted to know Rb, Sr, and Pb partitioning between aqueous fluids and melts [4]. There is a positive correlation between partition coefficients and pressure, as well as salinity. Two slab-derived components, melt and fluid components, are suggested to explain trace element characteristics of arc-basalts in the Mariana arc [5]. The fluid component is characterized by enrichment of alkali and alkali earth elements. Such features can be explained if the fluid component is a saline fluid, because alkali earth elements and Pb are much less mobile with Cl-free fluids than Cl-rich fluids [4]. We suggest that slab-derived components have compositional features consistent with a saline fluid and a melt, which can be formed through a separation of a slab-derived supercritical fluid [1]. Slab derived supercritical fluids contain Cl, and aqueous fluids inherit much of the Cl and some of the large-ion lithophile elements. [1] Kawamoto et al. 2012, Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism. PNAS, pnas.org/content/109/46/18695 [2] Kumagai et al. Evolution of carbon dioxide bearing saline fluids in the mantle wedge beneath the Northeast Japan arc, CMP [3] Kawamoto et al. 2013, Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab. PNAS, pnas.org/content/110/24/9663 [4] Kawamoto et al. 2014, Large ion

  11. Diacylglycerol Kinases Are Widespread in Higher Plants and Display Inducible Gene Expression in Response to Beneficial Elements, Metal, and Metalloid Ions.

    PubMed

    Escobar-Sepúlveda, Hugo F; Trejo-Téllez, Libia I; Pérez-Rodríguez, Paulino; Hidalgo-Contreras, Juan V; Gómez-Merino, Fernando C

    2017-01-01

    Diacylglycerol kinases (DGKs) are pivotal signaling enzymes that phosphorylate diacylglycerol (DAG) to yield phosphatidic acid (PA). The biosynthesis of PA from phospholipase D (PLD) and the coupled phospholipase C (PLC)/DGK route is a crucial signaling process in eukaryotic cells. Next to PLD, the PLC/DGK pathway is the second most important generator of PA in response to biotic and abiotic stresses. In eukaryotic cells, DGK, DAG, and PA are implicated in vital processes such as growth, development, and responses to environmental cues. A plethora of DGK isoforms have been identified so far, making this a rather large family of enzymes in plants. Herein we performed a comprehensive phylogenetic analysis of DGK isoforms in model and crop plants in order to gain insight into the evolution of higher plant DGKs. Furthermore, we explored the expression profiling data available in public data bases concerning the regulation of plant DGK genes in response to beneficial elements and other metal and metalloid ions, including silver (Ag), aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and sodium (Na). In all plant genomes explored, we were able to find DGK representatives, though in different numbers. The phylogenetic analysis revealed that these enzymes fall into three major clusters, whose distribution depends on the composition of structural domains. The catalytic domain conserves the consensus sequence GXGXXG/A where ATP binds. The expression profiling data demonstrated that DGK genes are rapidly but transiently regulated in response to certain concentrations and time exposures of beneficial elements and other ions in different plant tissues analyzed, suggesting that DGKs may mediate signals triggered by these elements. Though this evidence is conclusive, further signaling cascades that such elements may stimulate during hormesis, involving the phosphoinositide signaling pathway and DGK genes and enzymes, remain to be elucidated.

  12. Diacylglycerol Kinases Are Widespread in Higher Plants and Display Inducible Gene Expression in Response to Beneficial Elements, Metal, and Metalloid Ions

    PubMed Central

    Escobar-Sepúlveda, Hugo F.; Trejo-Téllez, Libia I.; Pérez-Rodríguez, Paulino; Hidalgo-Contreras, Juan V.; Gómez-Merino, Fernando C.

    2017-01-01

    Diacylglycerol kinases (DGKs) are pivotal signaling enzymes that phosphorylate diacylglycerol (DAG) to yield phosphatidic acid (PA). The biosynthesis of PA from phospholipase D (PLD) and the coupled phospholipase C (PLC)/DGK route is a crucial signaling process in eukaryotic cells. Next to PLD, the PLC/DGK pathway is the second most important generator of PA in response to biotic and abiotic stresses. In eukaryotic cells, DGK, DAG, and PA are implicated in vital processes such as growth, development, and responses to environmental cues. A plethora of DGK isoforms have been identified so far, making this a rather large family of enzymes in plants. Herein we performed a comprehensive phylogenetic analysis of DGK isoforms in model and crop plants in order to gain insight into the evolution of higher plant DGKs. Furthermore, we explored the expression profiling data available in public data bases concerning the regulation of plant DGK genes in response to beneficial elements and other metal and metalloid ions, including silver (Ag), aluminum (Al), arsenic (As), cadmium (Cd), chromium (Cr), mercury (Hg), and sodium (Na). In all plant genomes explored, we were able to find DGK representatives, though in different numbers. The phylogenetic analysis revealed that these enzymes fall into three major clusters, whose distribution depends on the composition of structural domains. The catalytic domain conserves the consensus sequence GXGXXG/A where ATP binds. The expression profiling data demonstrated that DGK genes are rapidly but transiently regulated in response to certain concentrations and time exposures of beneficial elements and other ions in different plant tissues analyzed, suggesting that DGKs may mediate signals triggered by these elements. Though this evidence is conclusive, further signaling cascades that such elements may stimulate during hormesis, involving the phosphoinositide signaling pathway and DGK genes and enzymes, remain to be elucidated. PMID:28223993

  13. Heavy-ion double charge exchange reactions: A tool toward 0 νββ nuclear matrix elements

    NASA Astrophysics Data System (ADS)

    Cappuzzello, F.; Cavallaro, M.; Agodi, C.; Bondì, M.; Carbone, D.; Cunsolo, A.; Foti, A.

    2015-11-01

    The knowledge of the nuclear matrix elements for the neutrinoless double beta decay is fundamental for neutrino physics. In this paper, an innovative technique to extract information on the nuclear matrix elements by measuring the cross section of a double charge exchange nuclear reaction is proposed. The basic point is that the initial- and final-state wave functions in the two processes are the same and the transition operators are similar. The double charge exchange cross sections can be factorized in a nuclear structure term containing the matrix elements and a nuclear reaction factor. First pioneering experimental results for the 40Ca(18O,18Ne)40Ar reaction at 270 MeV incident energy show that such cross section factorization reasonably holds for the crucial 0+ → 0+ transition to 40Args, at least at very forward angles.

  14. Effect of ceramic conversion treatments on the surface damage and nickel ion release of NiTi alloys under fretting corrosion conditions.

    PubMed

    Dong, H; Ju, X; Yang, H; Qian, L; Zhou, Z

    2008-02-01

    Recent researches have demonstrated that surface modification can improve the fretting wear resistance of NiTi alloys in air or enhance their aqueous corrosion resistance without fretting. However, little is known about the behaviour of surface engineered NiTi under fretting corrosion conditions. This is important for such body implants as orthodontic arch wires and orthopedic bone fixation devices because they need to withstand the combined attack of corrosion from body fluid and mechanical fretting. In this study, a NiTi alloy was ceramic conversion (CC) treated at 400 and 650 degrees C. The effect of the surface treatment on the fretting corrosion behaviour of NiTi alloy was investigated using fretting corrosion tests in the Ringer's solution. The experimental results have shown that the CC treatment can convert the surface of NiTi into a TiO2 layer, which can effectively improve the fretting corrosion resistance of NiTi alloy and significantly reduce Ni ion release into the Ringer's solution. Detailed SEM observations revealed that the untreated samples were severely damaged by adhesion and delamination; the high temperature (HT) (650 degrees C/1 h) treated samples were damaged mainly by spallation and adhesion; and the low temperature (LT) (400 degrees C/50 h) treated samples were characterised by mild abrasion. Mild oxidation and corrosion were also observed for all three types of samples tested under fretting corrosion conditions.

  15. In vitro metal ion release and biocompatibility of amorphous Mg67Zn28Ca5 alloy with/without gelatin coating.

    PubMed

    Chan, W Y; Chian, K S; Tan, M J

    2013-12-01

    Amorphous zinc-rich Mg-Zn-Ca alloys have exhibited good tissue compatibility and low hydrogen evolution in vivo. However, suboptimal cell-surface interaction on magnesium alloy surface observed in vitro could lead to reduced integration with host tissue for regenerative purpose. This study aims to improve cell-surface interaction of amorphous Mg67Zn28Ca5 alloy by coating a gelatin layer by electrospinning. Coated/uncoated alloys were immersed and extracted for 3 days under different CO2. The immersion results showed that pH and metal ion release in the alloy extracts were affected by gelatin coating and CO2, suggesting their roles in alloy biocorrosion and a mechanism has been proposed for the alloy-CO2 system with/without coating. Cytotoxicity results are evident that gelatin-coated alloy with 2-day crosslinking not only exhibited no indirect cytotoxicity, but also supported attachment of L929 and MG63 cell lines around/on the alloy with high viability. Therefore, amorphous Mg67Zn28Ca5 alloy coated with gelatin by electrospinning technique provides a useful method to improve alloy biocompatibility.

  16. Simultaneous determination of components released from dental composite resins in human saliva by liquid chromatography/multiple-stage ion trap mass spectrometry.

    PubMed

    Hsu, Wei-Yi; Wang, Ven-Shing; Lai, Chien-Chen; Tsai, Fuu-Jen

    2012-02-01

    Dental composite resins are widely used for fixing teeth; however, the monomers used in dental composite resins have been found to be cytotoxic and genotoxic, namely triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A glycol dimethacrylate (Bis-GMA). In this study, we incubated dental composite resins with human saliva for demonstrating the released monomers and biodegradation products. A simple saliva sample dilution method without purification or derivatization was used for quantification. We found that liquid chromatography coupled with multiple-stage ion trap mass spectrometry (LC-MS(n) ) operated in selected reaction monitoring (SRM) mode was able to separate the three monomers within 10 min. The calibration curves were linear (R² >0.996) over a wide range for each monomer in saliva: TEGDMA, 5-500 ppb; UDMA, 5-100 ppb, and Bis-GMA, 5-700 ppb. Furthermore, several biodegradation products were discovered with data-dependent MS/MS scan techniques. Although TEGMA degradation products have previously been reported, we identified two previously unknown UDMA degradation products. The LC-MS/MS method developed in this study was able to successfully quantify monomers and their principal biodegradation products from dental composite resins in human saliva.

  17. L shell x ray production in high-Z elements using 4-6 MeV/u fluorine ions

    NASA Astrophysics Data System (ADS)

    Kumar, Sunil; Singh, Udai; Oswal, M.; Singh, G.; Singh, N.; Mehta, D.; Nandi, T.; Lapicki, G.

    2017-03-01

    L shell line and total x ray production cross sections in 78Pt, 79Au, 82Pb, 83Bi, 90Th, and 92U targets ionized by 4-6 MeV/u fluorine ions were measured. These cross sections are compared with available theories for L shell ionization using single- and multiple-hole fluorescence and the Coster-Kronig yields. The ECPSSR and the ECUSAR theories exhibit good agreement with the measured data, whereas, the FBA theory overestimates them by a factor of two. Although for the F ion charge states q = 6-8 the multiple-hole atomic parameters do not significantly differ from the single-hole values, after an account for the multiple-holes, our data are better in agreement with the ECUSAR than the ECPSSR theory.

  18. Detector Calibration to Spontaneous Fission for the Study of Superheavy Elements Using Gas-Filled Recoil Ion Separator

    NASA Astrophysics Data System (ADS)

    Takeyama, Mirei; Kaji, Daiya; Morimoto, Kouji; Wakabayashi, Yasuo; Tokanai, Fuyuki; Morita, Kosuke

    Detector response to spontaneous fission (SF) of heavy nuclides produced in the 206Pb(48Ca,2n)252No reaction was investigated using a gas-filled recoil ion separator (GARIS). Kinetic energy distributions of the SF originating from 252No were observed by tuning implantation depth of evaporation residue (ER) to the detector. The focal plane detector used in the GARIS experiments was well calibrated by comparing with the known total kinetic energy (TKE) of SF due to 252No. The correction value for the TKE calculation was deduced as a function of the implantation depth of 252No to the detector. Furthermore, we have investigated the results by comparing with those obtained by a computer simulation using the particle and heavy ion transport code system (PHITS).

  19. Effects of trace elements on the crystal field parameters of Nd ions at the surface of Nd{sub 2}Fe{sub 14}B grains

    SciTech Connect

    Toga, Yuta; Suzuki, Tsuneaki; Sakuma, Akimasa

    2015-06-14

    Using first-principles calculations, we investigate the positional dependence of trace elements such as O and Cu on the crystal field parameter A{sub 2}{sup 0}, proportional to the magnetic anisotropy constant K{sub u} of Nd ions placed at the surface of Nd{sub 2}Fe{sub 14}B grains. The results suggest the possibility that the A{sub 2}{sup 0} parameter of Nd ions at the (001) surface of Nd{sub 2}Fe{sub 14}B grains exhibits a negative value when the O or Cu atom is located near the surface, closer than its equilibrium position. At the (110) surface, however, O atoms located at the equilibrium position provide a negative A{sub 2}{sup 0}, while for Cu additions A{sub 2}{sup 0} remains positive regardless of Cu's position. Thus, Cu atoms are expected to maintain a positive local K{sub u} of surface Nd ions more frequently than O atoms when they approach the grain surfaces in the Nd-Fe-B grains.

  20. Determination of elemental and ionic compositions for diesel exhaust particles by particle induced X-ray emission and ion chromatography analysis.

    PubMed

    Saitoh, Katsumi; Sera, Koichiro; Shirai, Tadashi; Sato, Tatsuji; Odaka, Matsuo

    2003-04-01

    The purpose of this study is to clarify the chemical characterization of PM2.5 and PM10 in diesel exhaust particles (DEP). Sampling of PM2.5 and PM10 in DEP was carried out in November 1999 using an automobile exhaust testing system at the National Traffic Safety and Environment Laboratory, with a diesel truck (engine type: direct injection, displacement: 7,961 cc, carrying weight: 2,020 kg, equivalent inertia weight: 5,600 kg) placed on a chassis dynamometer. Sampling conditions included idling, constant speed of 40 km/h, M-15 test pattern and 60%-revolution/40%-load of maximum power. Samples were collected on a polycarbonate membrane filter (Nuclepore, pore size: 0.8 microm) using a MiniVol Portable Air Sampler (Airmetrics Co., Inc.). The concentrations of several elemental and ionic species in the PM2.5 and PM10 samples were determined by particle induced X-ray emission (PIXE) and ion chromatography analysis. PIXE analysis of the PM2.5 and PM10 samples revealed 15 elements, of which Na, Mg, Si, S, Cl, Ca, Fe and Zn were found to be the major components. Ionic species were Cl-, NO2-, NO3-, SO4(2-), Na+, NH4+, K+ and Ca2+. Concentrations of elements and ionic species under the sampling condition of 60%-revolution/40%-load were highest in comparison with those of the other sampling conditions. The elemental and ionic species data were compared for PM2.5 and PM10; PM2.5 concentrations were 70% or more of PM10 concentrations for the majority of elements, and concentrations of ionic species in PM2.5 and PM10 were almost identical.

  1. Detection of fuel release in a nuclear accident: a method for preconcentration and isolation of reactor-borne (239)Np using ion-specific extraction chromatography.

    PubMed

    Rosenberg, Brett L; Shozugawa, Katsumi; Steinhauser, Georg

    2015-09-01

    Although actinides are the most informative elements with respect to the nature of a nuclear accident, plutonium analysis is complicated by the background created by fallout from atmospheric nuclear explosions. Therefore, we propose (239)Np, a short-lived actinide that emits several γ rays, as a preferred proxy. The aim of this study was to screen ion specific extraction chromatography resins (RE-, TEVA-, UTEVA-, TRU-, and Actinide-Resin) for the highest possible recovery and separation of trace amounts of (239)Np from samples with large activities of fission products such as radiocesium, radioiodine, and, most importantly, radiotellurium, the latter of which causes spectral interference in gamma spectrometry through overlapping peaks with (239)Np. The investigated environmental media for these separations were aqueous solutions simulating rainwater and soil. Spiked samples containing (239)Np and the aforementioned volatile radionuclides were separated through extraction chromatographic columns to ascertain the most effective means of separating (239)Np from other fission products for detection by gamma spectroscopy. We propose a method for nuclear accident preparedness based on the use of Eichrom's RE-Resin. The proposed method was found most effective for isolating (239)Np from interfering radionuclides in both aqueous solution and soil using 8 M HNO3 as the loading solution and H2O as the eluent. The RE-Resin outperforms the more commonly used TEVA-Resin because the TEVA-Resin showed a higher affinity for interfering radiotellurium and radioiodine.

  2. Stable Chlorine Isotopes and Elemental Chlorine by Thermal Ionization Mass Spectrometry and Ion Chromatography; Martian Meteorites, Carbonaceous Chondrites and Standard Rocks

    NASA Technical Reports Server (NTRS)

    Nakamura, N.; Nyquist, L. E.; Reese, Y.; Shih, C.-Y.; Fujitani, T.; Okano, O.

    2011-01-01

    Recently significantly large mass fractionation of stable chlorine isotopes has been reported for terrestrial and lunar samples [1,2]. In addition, in view of possible early solar system processes [3] and also potential perchlorate-related fluid/microbial activities on the Martian surface [4,5], a large chlorine isotopic fractionation might be expected for some types of planetary materials. Due to analytical difficulties of isotopic and elemental analyses, however, current chlorine analyses for planetary materials are controversial among different laboratories, particularly between IRMS (gas source mass spectrometry) and TIMS (Thermal Ionization Mass Spectrometry) groups [i.e. 1,6,7] for isotopic analyses, as well as between those doing pyrohydrolysis and other groups [i.e. 6,8]. Additional careful investigations of Cl isotope and elemental abundances are required to confirm real chlorine isotope and elemental variations for planetary materials. We have developed a TIMS technique combined with HF-leaching/ion chromatography at NASA JSC that is applicable to analysis of small amounts of meteoritic and planetary materials. We present here results for several standard rocks and meteorites, including Martian meteorites.

  3. Source Regions of the Interplanetary Magnetic Field and Variability in Heavy-Ion Elemental Composition in Gradual Solar Energetic Particle Events

    NASA Technical Reports Server (NTRS)

    Ko, Yuan-Kuen; Tylka, Allan J.; Ng, Chee K.; Wang, Yi-Ming; Dietrich, William F.

    2013-01-01

    Gradual solar energetic particle (SEP) events are those in which ions are accelerated to their observed energies by interactions with a shock driven by a fast coronal mass-ejection (CME). Previous studies have shown that much of the observed event-to-event variability can be understood in terms of shock speed and evolution in the shock-normal angle. But an equally important factor, particularly for the elemental composition, is the origin of the suprathermal seed particles upon which the shock acts. To tackle this issue, we (1) use observed solar-wind speed, magnetograms, and the PFSS model to map the Sun-L1 interplanetary magnetic field (IMF) line back to its source region on the Sun at the time of the SEP observations; and (2) then look for correlation between SEP composition (as measured by Wind and ACE at approx. 2-30 MeV/nucleon) and characteristics of the identified IMF-source regions. The study is based on 24 SEP events, identified as a statistically-significant increase in approx. 20 MeV protons and occurring in 1998 and 2003-2006, when the rate of newly-emergent solar magnetic flux and CMEs was lower than in solar-maximum years and the field-line tracing is therefore more likely to be successful. We find that the gradual SEP Fe/O is correlated with the field strength at the IMF-source, with the largest enhancements occurring when the footpoint field is strong, due to the nearby presence of an active region. In these cases, other elemental ratios show a strong charge-to-mass (q/M) ordering, at least on average, similar to that found in impulsive events. These results lead us to suggest that magnetic reconnection in footpoint regions near active regions bias the heavy-ion composition of suprathermal seed ions by processes qualitatively similar to those that produce larger heavy-ion enhancements in impulsive SEP events. To address potential technical concerns about our analysis, we also discuss efforts to exclude impulsive SEP events from our event sample.

  4. Phytotoxicity of ZnO nanoparticles and the released Zn(II) ion to corn (Zea mays L.) and cucumber (Cucumis sativus L.) during germination.

    PubMed

    Zhang, Ruichang; Zhang, Haibo; Tu, Chen; Hu, Xuefeng; Li, Lianzhen; Luo, Yongming; Christie, Peter

    2015-07-01

    Toxicity of engineered nanoparticles on organisms is of concern worldwide due to their extensive use and unique properties. The impacts of ZnO nanoparticles (ZnO NPs) on seed germination and root elongation of corn (Zea mays L.) and cucumber (Cucumis sativus L.) were investigated in this study. The role of seed coats of corn in the mitigation toxicity of nanoparticles was also evaluated. ZnO NPs (1,000 mg L(-1)) reduced root length of corn and cucumber by 17 % (p < 0.05) and 51 % (p < 0.05), respectively, but exhibited no effects on germination. In comparison with Zn(2+), toxicity of ZnO NPs on the root elongation of corn could be attributed to the nanoparticulate ZnO, while released Zn ion from ZnO could solely contribute to the inhibition of root elongation of cucumber. Zn uptake in corn exposed to ZnO NPs during germination was much higher than that in corn exposed to Zn(2+), whereas Zn uptake in cucumber was significantly correlated with soluble Zn in suspension. It could be inferred that Zn was taken up by corn and cucumber mainly in the form of ZnO NPs and soluble Zn, respectively. Transmission electron microscope confirmed the uptake of ZnO NPs into root of corn. Although isolation of the seed coats might not be the principal factor that achieved avoidance from toxicity on germination, seed coats of corn were found to mitigate the toxicity of ZnO NPs on root elongation and prevent approximately half of the Zn from entering into root and endosperm.

  5. Rb, Sr and strontium isotopic composition, K/Ar age and large ion lithophile trace element abundances in rocks and glasses from the Wanapitei Lake impact structure

    NASA Technical Reports Server (NTRS)

    Winzer, S. R.; Lum, R. K. L.; Schuhmann, S.

    1976-01-01

    Shock metamorphosed rocks and shock-produced melt glasses from the Wanapitei Lake impact structure have been examined petrographically and by electron microprobe. Eleven clasts exhibiting varying degrees of shock metamorphism and eight impact-produced glasses have been analyzed for Rb, Sr and Sr isotopic composition. Five clasts and one glass have also been analyzed for large ion lithophile (LIL) trace element abundances including Li, Rb, Sr, and Ba and the REE's. The impact event forming the Wanapitei Lake structure occurred 37 m.y. ago based on K/Ar dating of glass and glassy whole-rock samples. Rb/Sr isotopic dating failed to provide a meaningful whole-rock or internal isochron. The isotopic composition of the glasses can be explained by impact-produced mixing and melting of metasediments.

  6. Ion Mobility Mass Spectrometry for Extracting Spectra of N-Glycans Directly from Incubation Mixtures Following Glycan Release: Application to Glycans from Engineered Glycoforms of Intact, Folded HIV gp120

    NASA Astrophysics Data System (ADS)

    Harvey, David J.; Sobott, Frank; Crispin, Max; Wrobel, Antoni; Bonomelli, Camille; Vasiljevic, Snezana; Scanlan, Christopher N.; Scarff, Charlotte A.; Thalassinos, Konstantinos; Scrivens, James H.

    2011-03-01

    The analysis of glycosylation from native biological sources is often frustrated by the low abundances of available material. Here, ion mobility combined with electrospray ionization mass spectrometry have been used to extract the spectra of N-glycans released with PNGase F from a serial titration of recombinantly expressed envelope glycoprotein, gp120, from the human immunodeficiency virus (HIV). Analysis was also performed on gp120 expressed in the α-mannosidase inhibitor, and in a matched mammalian cell line deficient in GlcNAc transferase I. Without ion mobility separation, ESI spectra frequently contained no observable ions from the glycans whereas ions from other compounds such as detergents and residual buffer salts were abundant. After ion mobility separation on a Waters T-wave ion mobility mass spectrometer, the N-glycans fell into a unique region of the ion mobility/ m/z plot allowing their profiles to be extracted with good signal:noise ratios. This method allowed N-glycan profiles to be extracted from crude incubation mixtures with no clean-up even in the presence of surfactants such as NP40. Furthermore, this technique allowed clear profiles to be obtained from sub-microgram amounts of glycoprotein. Glycan profiles were similar to those generated by MALDI-TOF MS although they were more susceptible to double charging and fragmentation. Structural analysis could be accomplished by MS/MS experiments in either positive or negative ion mode but negative ion mode gave the most informative spectra and provided a reliable approach to the analysis of glycans from small amounts of glycoprotein.

  7. Characterization of flux-grown Trace-element-doped titanite using the high-mass-resolution ion microprobe (SHRIMP-RG)

    USGS Publications Warehouse

    Mazdab, F.K.

    2009-01-01

    Crystals of titanite can be readily grown under ambient pressure from a mixture of CaO, TiO2 and SiO2 in the presence of molten sodium tetraborate. The crystals produced are euhedral and prismatic, lustrous and transparent, and up to 5 mm in length. Titanite obtained by this method contains approximately 4300 ppm Na and 220 ppm B contributed from the flux. In addition to dopant-free material, titanite containing trace alkali and alkaline earth metals (K, Sr, Ba), transition metals (Sc, Cr, Ni, Y, Zr, Nb, Hf and Ta), rare-earth elements (REE), actinides (Th, U) and p-block elements (F, S, Cl, Ge, Sn and Pb) have been prepared using the same procedure. Back-scattered electron (BSE) imaging accompanied by ion-microprobe (SHRIMP-RG) analysis confirms significant incorporation of selected trace-elements at structural sites. Regardless of some zonation, the large size of the crystals and broad regions of chemical homogeneity make these crystals useful as experimental starting material, and as matrix-matched trace-element standards for a variety of microbeam analytical techniques where amorphous titanite glass, heterogeneous natural titanite or a non-titanite standard may be less than satisfactory. Trace-element-doped synthetic crystals can also provide a convenient proxy for a better understanding of trace-element incorporation in natural titanite. Comparisons with igneous, authigenic and high-temperature metasomatic titanite are examined. The use of high-mass-resolution SIMS also demonstrates the analytical challenges inherent to any in situ mass-spectrometry-based analysis of titanite, owing to the production of difficult-to-resolve molecular interferences. These interferences are dominated by Ca-Ca, Ca-Ti and Ti-Ti dimers that are significant in the mass range of 80-100, affecting all isotopes of Sr and Zr, as well as 89Y and 93Nb. Methods do exist for the evaluation of interferences by these dimers and of polyatomic interferences on the LREE.

  8. Uranium hydrogeochemical and stream sediment reconnaissance data release for the Elk City NTMS Quadrangle, Idaho/Montana, including concentrations of forty-five additional elements

    SciTech Connect

    Broxton, D.E.; Beyth, M.

    1980-07-01

    Totals of 1580 water and 1720 sediment samples were collected from 1754 locations in the quadrangle. Elemental concentration, field measurement, weather, geologic, and geographic data for each sample location are listed for waters in Appendix I-A and for sediments in Appendix I-B. Uranium/thorium ratios for sediment samples are also included in Appendix I-B. All elemental analyses were performed at the LASL. Water samples were initially analyzed for uranium by fluorometry. All water samples containing more than 40 parts per billion (ppB) uranium were reanalyzed by delayed-neutron counting (DNC). A supplemental report containing the multielement analyses of water samples will be open filed in the near future. Sediments were analyzed for uranium and thorium as well as aluminum, antimony, arsenic, barium, beryllium, bismuth, cadmium, calcium, cerium, cesium, chlorine, chromium, cobalt, copper, dysprosium, europium, gold, hafnium, iron, lanthanum, lead, lithium, lutetium, magnesium, manganese, nickel, niobium, potassium, rubidium, samarium, selenium, scandium, silver, sodium, strontium, tantalum, terbium, tin, titanium, tungsten, vanadium, ytterbium, zinc, and zirconium. Basic statistics for 40 of these elements are presented. All sediments were analyzed for uranium by delayed-neutron counting. Other elemental concentrations in sediments were determined by neutron-activation analysis for 30 elements, by x-ray fluorescence for 12 elements, and by arc-source emission spectrography for 2 elements. Analytical results for sediments are reported as parts per million.

  9. Role of the transient receptor potential vanilloid type 1 receptor and stretch-activated ion channels in nitric oxide release from endothelial cells of the aorta and heart in rats

    PubMed Central

    Torres-Narváez, Juan Carlos; Mondragón, Leonardo del Valle; Varela López, Elvira; Pérez-Torres, Israel; Díaz Juárez, Julieta Anabell; Suárez, Jorge; Hernández, Gustavo Pastelín

    2012-01-01

    Shear stress stimulates nitric oxide (NO) release in endothelial cells. Stretch-activated ion channels (SACs) and the transient receptor potential vanilloid type 1 (TRPV1) receptor respond to mechanical stimulus and are permeable to Na+, Ca2+ and K+. The influence of SACs and the TRPV1 receptor on NO release on the heart and on the vascular reactivity of the thoracic aorta (TA) was studied. Experiments were performed in isolated perfused heart, cultured endothelial cells and TA rings from Wistar rats. Capsaicin (10 μM, 30 μM) was used as a NO release stimulator, capsazepine (6 μM, 10 μM) was used as a capsaicin antagonist and gadolinium (3 μM, 5 μM) was used as an inhibitor of SACs. NO was measured by the Kelm and Tenorio methods. Left ventricular pressure was recorded and coronary vascular resistance was calculated. Capsaicin increased NO release in the heart by 58% (395±8 pmol/mL to 627±23 pmol/mL). Capsazepine and gadolinium inhibited NO release by 74% and 82%, respectively. This tendency was similar in all experimental models. Capsaicin attenuated the effects of norepinephrine (10 M to 7 M) on TA and had no effect in the presence of Nω-nitro-L-arginine methyl ester. Therefore, the authors conclude that SACs and the TRPV1 receptor are both present in the coronary endothelium and that both participate in Ca2+-dependent NO release. PMID:23620694

  10. Controlled Release of Biologically Active Silver from Nanosilver Surfaces

    PubMed Central

    Liu, Jingyu; Sonshine, David A.; Shervani, Saira; Hurt, Robert H.

    2010-01-01

    Major pathways in the antibacterial activity and eukaryotic toxicity of nano-silver involve the silver cation and its soluble complexes, which are well established thiol toxicants. Through these pathways, nano-silver behaves in analogy to a drug delivery system, in which the particle contains a concentrated inventory of an active species, the ion, which is transported to and released near biological target sites. Although the importance of silver ion in the biological response to nano-silver is widely recognized, the drug delivery paradigm has not been well developed for this system, and there is significant potential to improve nano-silver technologies through controlled release formulations. This article applies elements of the drug delivery paradigm to nano-silver dissolution and presents a systematic study of chemical concepts for controlled release. After presenting thermodynamic calculations of silver species partitioning in biological media, the rates of oxidative silver dissolution are measured for nanoparticles and macroscopic foils and used to derive unified area-based release kinetics. A variety of competing chemical approaches are demonstrated for controlling the ion release rate over four orders of magnitude. Release can be systematically slowed by thiol and citrate ligand binding, formation of sulfidic coatings, or the scavenging of peroxy-intermediates. Release can be accelerated by pre-oxidation or particle size reduction, while polymer coatings with complexation sites alter the release profile by storing and release inventories of surface-bound silver. Finally, the ability to tune biological activity is demonstrated through bacterial inhibition zone assay carried out on selected formulations of controlled release nano-silver. PMID:20968290

  11. Determination of the abundance of delta15N in nitrate ion in contaminated groundwater samples using an elemental analyzer coupled to a mass spectrometer.

    PubMed

    Ogawa, Y; Nishikawa, M; Nakasugi, O; Ii, H; Hirata, T

    2001-07-01

    A rapid method for measuring the delta15N of nitrate ion in water samples using an isotope ratio mass spectrometer coupled to an elemental analyzer system (EA-MS) was investigated. The water should be removed from the analytical sample before measurement with this system. We investigated the application of a super-absorbent polymer resin powder to various water samples. Each 1 mg of polymer resin powder can absorb about 50-100 mg of solution depending on the concentrations of major ions. Only samples which contain more than 100 mg l(-1) of nitrate-nitrogen are suitable to be absorbed by the polymer resin for the determination of delta15N of nitrate. Preconcentration by rotary evaporation was necessary for dilute samples but the temperature should be kept below 60 degrees C. The polymer resin (about 8 mg) containing the nitrate was directly analyzed using an EA-MS after being oven-dried at 80 degrees C. Good accuracy (precision +/- 0.3%) for delta15N measurements of nitrate-nitrogen in a sample without any isotope fractionation effects during pre-treatment was observed. Results for delta15N of nitrate in contaminated groundwater samples collected in the spring at a tea plantation area in Shizuoka, Japan, were from 9.8 to 10.6%, which were close to the delta15N abundance in organic fertilizers.

  12. CdSe@ZnS nanocomposites prepared by a mechanochemical route: No release of Cd{sup 2+} ions and negligible in vitro cytotoxicity

    SciTech Connect

    Baláž, Peter; Sayagués, Maria Jesús; Baláž, Matej; Zorkovská, Anna; Hronec, Pavol; Kováč, Jaroslav; Kováč, Jaroslav; Dutková, Erika; Mojžišová, Gabriela; and others

    2014-01-01

    Graphical abstract: - Highlights: • CdSe@ZnS nanocomposites were produced by milling. • Negligible cadmium leakage was observed. • No toxicity against living cells was documented. • The material is suitable for biological imaging. - Abstract: CdSe@ZnS nanocomposites have been prepared by a two-step solid state mechanochemical synthesis. CdSe prepared from Cd and Se elements in the first step was mixed with zinc acetate and sodium sulphide in the second step of milling to prepare a CdSe@ZnS nanocomposite. In the third step, the obtained nanocomposite was coated with L-cysteine to prepare a biocompatible system. The crystallite size of the new type of nanocomposite was 20–35 nm for cubic CdSe and 3–8 nm for hexagonal ZnS as calculated from XRD, TEM and SEM data. The synthesised samples show good crystallinity and have been tested for dissolution and cytotoxicity. The dissolution of cadmium from CdSe@ZnS was less than 0.05 μg mL{sup −1}, whereas a value of 0.8 μg mL{sup −1} was measured for CdSe alone. The binding of ZnS with CdSe in the nanocomposite practically eliminated the release of cadmium into solution. As a consequence, a very low cytotoxic activity has been evidenced for CdSe@ZnS. The nanocomposites coated with L-cysteine have a great potential as fluorescent labels in biomedical engineering.

  13. Combined elemental analysis of ancient glass beads by means of ion beam, portable XRF, and EPMA techniques.

    PubMed

    Sokaras, D; Karydas, A G; Oikonomou, A; Zacharias, N; Beltsios, K; Kantarelou, V

    2009-12-01

    Ion beam analysis (IBA)- and X-ray fluorescence (XRF)-based techniques have been well adopted in cultural-heritage-related analytical studies covering a wide range of diagnostic role, i.e., from screening purposes up to full quantitative characterization. In this work, a systematic research was carried out towards the identification and evaluation of the advantages and the limitations of laboratory-based (IBA, electron probe microanalyzer) and portable (milli-XRF and micro-XRF) techniques. The study focused on the analysis of an Archaic glass bead collection recently excavated from the city of Thebes (mainland, Greece), in order to suggest an optimized and synergistic analytical methodology for similar studies and to assess the reliability of the quantification procedure of analyses conducted in particular by portable XRF spectrometers. All the employed analytical techniques and methodologies proved efficient to provide in a consistent way characterization of the glass bead composition, with analytical range and sensitivity depending on the particular technique. The obtained compositional data suggest a solid basis for the understanding of the main technological features related to the raw major and minor materials utilized for the manufacture of the Thebian ancient glass bead collection.

  14. Exploration of multi-fold symmetry element-loaded superconducting radio frequency structure for reliable acceleration of low- & medium-beta ion species

    SciTech Connect

    Huang, Shichun; Geng, Rongli

    2015-09-01

    Reliable acceleration of low- to medium-beta proton or heavy ion species is needed for future high-current superconducting radio frequency (SRF) accelerators. Due to the high-Q nature of an SRF resonator, it is sensitive to many factors such as electron loading (from either the accelerated beam or from parasitic field emitted electrons), mechanical vibration, and liquid helium bath pressure fluctuation etc. To increase the stability against those factors, a mechanically strong and stable RF structure is desirable. Guided by this consideration, multi-fold symmetry element-loaded SRF structures (MFSEL), cylindrical tanks with multiple (n>=3) rod-shaped radial elements, are being explored. The top goal of its optimization is to improve mechanical stability. A natural consequence of this structure is a lowered ratio of the peak surface electromagnetic field to the acceleration gradient as compared to the traditional spoke cavity. A disadvantage of this new structure is an increased size for a fixed resonant frequency and optimal beta. This paper describes the optimization of the electro-magnetic (EM) design and preliminary mechanical analysis for such structures.

  15. Detection of mercury ions using silver telluride nanoparticles as a substrate and recognition element through surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Wang, Chia-Wei; Lin, Zong-Hong; Roy, Prathik; Chang, Huan-Tsung

    2013-10-01

    In this paper we unveil a new sensing strategy for sensitive and selective detection of Hg2+ through surface-enhanced Raman scattering (SERS) using Ag2Te nanoparticles (NPs) as a substrate and recognition element and rhodamine 6G (R6G) as a reporter. Ag2Te NPs prepared from tellurium dioxide and silver nitrate and hydrazine in aqueous solution containing sodium dodecyl sulfate at 90ºC with an average size of 26.8 ± 4.1 nm (100 counts) have strong SERS activity. The Ag2Te substrate provides strong SERS signals of R6G with an enhancement factor of 3.6 × 105 at 1360 cm-1, which is comparable to Ag NPs. After interaction of Ag2Te NPs with Hg2+, some HgTe NPs are formed, leading to decreases in the SERS signal of R6G, mainly because HgTe NPs relative to Ag2Te NPs have weaker SERS activity. Under optimum conditions, this SERS approach using Ag2Te as substrates is selective for the detection of Hg2+, with a limit of detection of 3 nM and linearity over 10-150 nM. The practicality of this approach has been validated for the determination of the concentrations of spiked Hg2+ in a pond water sample.

  16. Uranium hydrogeochemical and stream sediment reconnaissance data release for the Dubois NTMS Quadrangle, Idaho/Montana, including concentrations of forty-five additional elements

    SciTech Connect

    LaDelfe, C.M.

    1980-08-01

    Totals of 1024 water samples and 1600 sediment samples were collected from 1669 locations in the Dubois quadrangle. Water samples were taken at streams, springs, and wells; sediment samples were collected from streams and springs. All field and analytical data are presented for waters in Appendix I-A and for sediments in I-B. All elemental analyses were performed at the LASL. Water samples were initially analyzed for uranium by fluorometry. All water samples containing more than the upper detection limit of uranium were reanalyzed by delayed neutron counting. Sediments were analyzed for uranium and thorium as well as aluminum, antimony, arsenic, barium, beryllium, bismuth, cadmium, calcium, cerium, cesium, chlorine, chromium, cobalt, copper, dysprosium, europium, gold, hafnium, iron, lanthanum, lead, lithium, lutetium, magnesium, manganese, nickel, niobium, potassium rubidium, samarium, scandium, selenium, silver, sodium, strontium, tantalum, terbium, tin, titanium, tungsten, vanadium, ytterbium, zinc and zirconium. All sediments were analyzed for uranium by delayed-neutron counting. Other elemental concentrations in sediments were determined by neutron-activation analysis for 30 elements, by x-ray fluorescence for 12 elements, and by arc-source emission spectrography for 2 elements. Analytical results for sediments are reported as parts per million.

  17. U-Th-Pb ion microprobe analysis of monazite from the Paleoproterozoic Karrat rare earth element (REE) deposit, western Greenland

    NASA Astrophysics Data System (ADS)

    Mott, A.; Grove, M.; Bird, D. K.

    2012-12-01

    The Karrat rare earth element (REE) deposit is located at 72°N on the Niaqornakavsak peninsula of Qeqertarssuq Island on the western coast of Greenland. Metasomatic alteration of an amphibolite host rock by carbonatite derived fluids resulted in REE mineralization in the Karrat Isfjord area. REE in the mineralization are primarily found in bastnasite, allanite, and monazite. In-situ analysis of monazite was conducted on samples obtained from three sites of mineralization: (1) the primary deposit at Niaqornakavsak consisting of a single distinct ~30m thick unit; (2) at Umiamako Nuna 7 km to the east of Niaqornakavsak where the majority of REE mineralization occurs within the first 20m of the surface; and (3) a 6m thick REE-rich vein 100m below the surface at Umiamako Nuna. Formation ages for monazite at Niaqornakavsak, Umiamako Nuna (surface), and Umiamako Nuna (vein) have been calculated using 207Pb/206Pb, 206Pb/238U, and 208Pb/232Th isotope ratios. Multiple isotope ratios were examined to determine the ideal method of monazite analysis based on the inherent issues of low U content of monazite, difficulties measuring 204Pb, common Pb corrections, and peak interferences resulting from high concentrations of REE. 208Pb/232Th analysis resulted in the best precision and smallest spread of values. Energy filtering was applied to 208Pb/232Th analyses in an effort to reduce interferences at several peaks. Although all three isotope ratio analyses result in a Paleoproterozoic age similar to the timing of convergence of the North Atlantic craton, Rae craton, and Aasiat domain as well as the emplacement of the Prøven Igneous Complex in Greenland (1.95-1.80Ga), the values range between 1.7-1.9Ga depending on the isotope ratio.

  18. Characteristics of releases from TREAT source term experiment STEP-3

    SciTech Connect

    Fink, J.K.; Schlenger, B.J.; Baker, L. Jr.; Ritzman, R.L.

    1987-01-01

    Four in-pile experiments designed to characterize the radiological source term associated with postulated severe light water reactor accidents were performed at the Transient Reactor Test Facility. STEP-3 simulated a high-pressure TMLB' pressurized water reactor accident sequence that includes the extended loss of all ac power and leads to the loss of long-term decay heat removal. In STEP-3, four fuel elements from the Belgonucleaire BR3 reactor were subjected to temperature and pressures approaching those of a TMLB' accident. A description of the experiment and thermal-hydraulic analysis is reported elsewhere. The aerosols released into the flow stream were collected on coupons, settling plates, and wire impactors. Examination of the collected aerosol deposits was performed using scanning electron microscopy, electron microprobe microanalysis, and secondary ion mass spectroscopy (SIMS), to provide information about the chemical composition and morphology of the release. This paper describes the aerosol deposits and elemental composition of the release.

  19. The effect of water vapor on the release of fission gas from the fuel elements of high temperature, gas-cooled reactors: A preliminary assessment of experiments HRB-17, HFR-B1, HFR-K6 and KORA

    SciTech Connect

    Myers, B.F.

    1995-09-01

    The effect of water vapor on the release of fission gas from the fuel elements of high temperature, gas-cooled reactors has been measured in different laboratories under both irradiation and post irradiation conditions. The data from experiments HRB-17, HFR-B1, HFR-K6, and in the KORA facility are compared to assess their consistency and complimentarily. The experiments are consistent under comparable experimental conditions and reveal two general mechanisms involving exposed fuel kernels embedded in carbonaceous materials. One is manifest as a strong dependence of fission gas release on the partial pressure of water vapor below 1 kPa and the other, as a weak dependence above 1 kPa.

  20. Uranium hydrogeochemical and stream sediment reconnaissance data release for the Lewistown NTMS Quadrangle, Montana, including concentrations of forty-two additional elements

    SciTech Connect

    Shannon, S.S. Jr.

    1980-08-01

    Totals of 758 water and 1170 sediment samples were collected from 1649 locations in the Levistown quadrangle. Water samples were collected at streams, springs, wells, ponds, and marshes; sediment samples were obtained from streams, springs, and ponds. Histograms and statistical data for uranium concentrations in water and sediment samples and thorium concentrations in sediment samples are given. All samples were collected at the nominal reconnaissance density of one sample location per 10 km/sup 2/. Elemental concentration, field measurement, weather, geologic, and geographic data for each sample location are listed for waters and for sediments. Uranium to thorium (U/Th) ratios for sediment samples are included. Water samples were initially analyzed for uranium by fluorometry. All water samples containing more than 40 ppB U were reanalyzed by delayed-neutron counting. Sediments were analyzed for U and Th as well as Al, Sb, Ba, Be, Bi, Cd, Ca, Ce, Cs, Cl, Cr, Co, Cu, Dy, Eu, Au, Hf, Fe, La, Pb, Li, Lu, Mg, Mn, Ni, Nb, K, Rb, Sa, Sc, Ag, Na, Sr, Ta, Tb, Sn, Ti, W, V, Yb, and Zn. All sediments were analyzed for U by delayed neutron counting. Other elemental concentrations in sediments were determined by neutron activation analysis for 31 elements, by x-ray fluorescence for 9 elements, and by arc-source emission spectrography for 2 elements. Analytical results are reported as parts per million. Descriptions of procedures used for analysis of water and sediments samples as well as analytical precisions and detection limits are given.

  1. A field measurement based scaling approach for quantification of major ions, organic carbon, and elemental carbon using a single particle aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Huang, X. H. Hilda; Griffith, Stephen M.; Li, Mei; Li, Lei; Zhou, Zhen; Wu, Cheng; Meng, Junwang; Chan, Chak K.; Louie, Peter K. K.; Yu, Jian Zhen

    2016-10-01

    Single Particle Aerosol Mass Spectrometers (SPAMS) have been increasingly deployed for aerosol studies in Asia. To date, SPAMS is most often used to provide unscaled information for both the size and chemical composition of individual particles. The instrument's lack of accuracy is primarily due to only a fraction of particles being detected after collection, and the instrumental sensitivity is un-calibrated for various chemical species in mixed ambient aerosols. During a campaign from January to April 2013 at a coastal site in Hong Kong, the particle number information and ion intensity of major PM2.5 components collected by SPAMS were scaled by comparing with collocated bulk PM2.5 measurements of hourly or higher resolution. The bulk measurements include PM2.5 mass by a SHARP 5030 Monitor, major ions by a Monitor for Aerosols & Gases in ambient Air (MARGA), and organic carbon (OC) and elemental carbon (EC) by a Sunset OCEC analyzer. During the data processing, both transmission efficiency (scaled with the Scanning Mobility Particle Sizer) and hit efficiency conversion were considered, and component ion intensities quantified as peak area (PA) and relative peak area (RPA) were analyzed to track the performance. The comparison between the scaled particle mass assuming a particle density of 1.9 g cm-3 from SPAMS and PM2.5 concentration showed good correlation (R2 = 0.81) with a slope of 0.814 ± 0.004. Regression analysis results suggest an improved scaling performance using RPA compared with PA for most of the major PM2.5 components, including sulfate, nitrate, potassium, ammonium, OC and EC. Thus, we recommend preferentially scaling these species using the RPA. For periods of high K+ concentrations (>1.5 μg m-3), under-estimation of K+ by SPAMS was observed due to exceeding the dynamic range of the acquisition board. When only applying the hit efficiency correction, data for sulfate, nitrate, ammonium, potassium and OC were in reasonably good correlation (R2 = 0

  2. Sulfate ion (SO4(2-)) release from old and new cation exchange resins used in condensate polishing systems for power plants.

    PubMed

    Zhu, Zhi-Ping; Tang, Xue-Ying; Yin, Zhao-Hui; Yu, Wei-Wei

    2014-01-01

    In this study, a dynamic cycle test, a static immersion method and a pyrolysis experiment were combined to examine the characteristics of SO4(2-) released from several new and old cation exchange resins used in condensate polishing systems for power plants. The results show that the quantity and velocity of SO4(2-) released from new and old resins tend to balance in a short time during the dynamic cycle experiment. SO4(2-) is released by 1500H (monosphere super gel type cation exchange resins) and 001 × 7 (gel type cation exchange resins) new and old cation exchange resins, the quantity of which increases according to immersion time. In the pyrolysis experiment, the quantity of SO4(2-) released from resins increases and the pH of the pyrolysis solution transforms from alkaline to acidic with an increase in temperature.

  3. Natural experimental charges: an ion-microprobe study of trace element distribution coefficients in glass-rich hornblendite and clinopyroxenite xenoliths

    NASA Astrophysics Data System (ADS)

    Downes, Hilary; Beard, Andrew; Hinton, Richard

    2004-07-01

    Igneous glasses found in hornblende- and clinopyroxene-rich xenoliths represent former melt pools and contain important information about magmatic processes in mafic alkaline magmas. Rare glass-bearing hornblendite and clinopyroxenite xenoliths entrained in intraplate alkali basalts from Germany and Israel contain up to 11% interstitial glass surrounded by euhedral crystals of mafic minerals (hornblende, clinopyroxene, phlogopite). These xenoliths represent natural experimental charges of alkaline magma quenched by rapid eruption whilst crystallising mafic mineral phases. Bulk rock compositions of the xenoliths are basanitic, considered as representing the starting compositions of the natural experiment, whereas the interstitial glasses are chemically more evolved (highly alkaline foidites) as a result of closed system crystallisation of mafic minerals. Ion-probe trace element data for glass and mineral phases (hornblende, clinopyroxene, phlogopite and apatite) yield in situ distribution coefficients ( KDs) between magma and minerals. The results generally confirm distribution coefficients derived from experimental data and from melt-bearing peridotite xenoliths, but tend to be slightly higher, perhaps because of the evolved nature of the melt. Disruption of these xenoliths, which must have been semi-consolidated when entrained, may help to explain the origin of clinopyroxene, amphibole and phlogopite megacrysts that are commonly observed in alkali basalts.

  4. Design and performance of a combined secondary ion mass spectrometry-scanning probe microscopy instrument for high sensitivity and high-resolution elemental three-dimensional analysis

    SciTech Connect

    Wirtz, Tom; Fleming, Yves; Gerard, Mathieu; Gysin, Urs; Glatzel, Thilo; Meyer, Ernst; Wegmann, Urs; Maier, Urs; Odriozola, Aitziber Herrero; Uehli, Daniel

    2012-06-15

    State-of-the-art secondary ion mass spectrometry (SIMS) instruments allow producing 3D chemical mappings with excellent sensitivity and spatial resolution. Several important artifacts however arise from the fact that SIMS 3D mapping does not take into account the surface topography of the sample. In order to correct these artifacts, we have integrated a specially developed scanning probe microscopy (SPM) system into a commercial Cameca NanoSIMS 50 instrument. This new SPM module, which was designed as a DN200CF flange-mounted bolt-on accessory, includes a new high-precision sample stage, a scanner with a range of 100 {mu}m in x and y direction, and a dedicated SPM head which can be operated in the atomic force microscopy (AFM) and Kelvin probe force microscopy modes. Topographical information gained from AFM measurements taken before, during, and after SIMS analysis as well as the SIMS data are automatically compiled into an accurate 3D reconstruction using the software program 'SARINA,' which was developed for this first combined SIMS-SPM instrument. The achievable lateral resolutions are 6 nm in the SPM mode and 45 nm in the SIMS mode. Elemental 3D images obtained with our integrated SIMS-SPM instrument on Al/Cu and polystyrene/poly(methyl methacrylate) samples demonstrate the advantages of the combined SIMS-SPM approach.

  5. Design and performance of a combined secondary ion mass spectrometry-scanning probe microscopy instrument for high sensitivity and high-resolution elemental three-dimensional analysis.

    PubMed

    Wirtz, Tom; Fleming, Yves; Gerard, Mathieu; Gysin, Urs; Glatzel, Thilo; Meyer, Ernst; Wegmann, Urs; Maier, Urs; Odriozola, Aitziber Herrero; Uehli, Daniel

    2012-06-01

    State-of-the-art secondary ion mass spectrometry (SIMS) instruments allow producing 3D chemical mappings with excellent sensitivity and spatial resolution. Several important artifacts however arise from the fact that SIMS 3D mapping does not take into account the surface topography of the sample. In order to correct these artifacts, we have integrated a specially developed scanning probe microscopy (SPM) system into a commercial Cameca NanoSIMS 50 instrument. This new SPM module, which was designed as a DN200CF flange-mounted bolt-on accessory, includes a new high-precision sample stage, a scanner with a range of 100 μm in x and y direction, and a dedicated SPM head which can be operated in the atomic force microscopy (AFM) and Kelvin probe force microscopy modes. Topographical information gained from AFM measurements taken before, during, and after SIMS analysis as well as the SIMS data are automatically compiled into an accurate 3D reconstruction using the software program "SARINA," which was developed for this first combined SIMS-SPM instrument. The achievable lateral resolutions are 6 nm in the SPM mode and 45 nm in the SIMS mode. Elemental 3D images obtained with our integrated SIMS-SPM instrument on Al/Cu and polystyrene/poly(methyl methacrylate) samples demonstrate the advantages of the combined SIMS-SPM approach.

  6. Design and performance of a combined secondary ion mass spectrometry-scanning probe microscopy instrument for high sensitivity and high-resolution elemental three-dimensional analysis

    NASA Astrophysics Data System (ADS)

    Wirtz, Tom; Fleming, Yves; Gerard, Mathieu; Gysin, Urs; Glatzel, Thilo; Meyer, Ernst; Wegmann, Urs; Maier, Urs; Odriozola, Aitziber Herrero; Uehli, Daniel

    2012-06-01

    State-of-the-art secondary ion mass spectrometry (SIMS) instruments allow producing 3D chemical mappings with excellent sensitivity and spatial resolution. Several important artifacts however arise from the fact that SIMS 3D mapping does not take into account the surface topography of the sample. In order to correct these artifacts, we have integrated a specially developed scanning probe microscopy (SPM) system into a commercial Cameca NanoSIMS 50 instrument. This new SPM module, which was designed as a DN200CF flange-mounted bolt-on accessory, includes a new high-precision sample stage, a scanner with a range of 100 μm in x and y direction, and a dedicated SPM head which can be operated in the atomic force microscopy (AFM) and Kelvin probe force microscopy modes. Topographical information gained from AFM measurements taken before, during, and after SIMS analysis as well as the SIMS data are automatically compiled into an accurate 3D reconstruction using the software program "SARINA," which was developed for this first combined SIMS-SPM instrument. The achievable lateral resolutions are 6 nm in the SPM mode and 45 nm in the SIMS mode. Elemental 3D images obtained with our integrated SIMS-SPM instrument on Al/Cu and polystyrene/poly(methyl methacrylate) samples demonstrate the advantages of the combined SIMS-SPM approach.

  7. Skin tissue engineering for the infected wound site: biodegradable PLA nanofibers and a novel approach for silver ion release evaluated in a 3D coculture system of keratinocytes and Staphylococcus aureus.

    PubMed

    Mohiti-Asli, Mahsa; Pourdeyhimi, Behnam; Loboa, Elizabeth G

    2014-10-01

    Wound infection presents a challenging and growing problem. With the increased prevalence and growth of multidrug-resistant bacteria, there is a mounting need to reduce and eliminate wound infections using methodologies that limit the ability of bacteria to evolve into further drug-resistant strains. A well-known strategy for combating bacterial infection and preventing wound sepsis is through the delivery of silver ions to the wound site. High surface area silver nanoparticles (AgNPs) allowing extensive silver ion release have therefore been explored in different wound dressings and/or skin substitutes. However, it has been recently shown that AgNPs can penetrate into the stratum corneum of skin or diffuse into the cellular plasma membrane, and may interfere with a variety of cellular mechanisms. The goal of this study was to introduce and evaluate a new type of high surface area metallic silver in the form of highly porous silver microparticles (AgMPs). Polylactic acid (PLA) nanofibers were successfully loaded with either highly porous AgMPs or AgNPs and the antimicrobial efficacy and cytotoxicity of the two silver-based wound dressings were assessed and compared. To better mimic the physiological environment in vivo where both human cells and bacteria are present, a novel coculture system combining human epidermal keratinocytes and Staphylococcus aureus bacteria was designed to simultaneously evaluate human skin cell cytotoxicity with antimicrobial efficacy in a three-dimensional environment. We found that highly porous AgMPs could be successfully incorporated in nanofibrous wound dressings, and exhibited comparable antimicrobial efficacy and cytotoxicity to AgNPs. Further, PLA nanofibers containing highly porous AgMPs exhibited steady silver ion release, at a greater rate of release, than nanofibers containing AgNPs. The replacement of AgNPs with the newly introduced AgMPs overcomes concerns regarding the use of nanoparticles and holds great promise as skin

  8. Dependence of kinetic variables in the short-term release of Hg2+, Cu2+ and Zn2+ ions into synthetic saliva from an high-copper dental amalgam.

    PubMed

    Campus, Guglielmo; Garcia-Godoy, Franklin; Gaspa, Leonardo; Panzanelli, Angelo; Piu, Paola C; Micera, Giovanni; Lugliè, Pierfranca; Sanna, Gavino

    2007-08-01

    The short term (up to 14 days after restoration) release of selected ions (i.e., Hg(2+), Cu(2+) and Zn(2+)) from Dispersalloy into artificial saliva has been evaluated in regards to the nature of the saliva (Fusayama and McCarty and Shklar's solutions), the amount of amalgam, the time of contact and the periodical renewal (every 48 h interval) of artificial saliva. The evaluation of the ionic fraction of such metals has been accomplished by using anodic stripping methods (i.e., Differential Pulse Anodic Stripping Voltammetry, DPASV) with a 7 microm graphite disk microelectrode as a working electrode. Data obtained in this work are almost unprecedented in the literature due the fact that such analytical method exclude metals in non-ionic forms (e.g., metals or organometallic compounds). The high concentrations measured in every experimental condition confirm the concern for the short-term release of metals from amalgam into saliva.

  9. Elemental characterization of PM2.5 and PM10 emitted from light duty vehicles in the Washburn Tunnel of Houston, Texas: release of rhodium, palladium, and platinum.

    PubMed

    Bozlaker, Ayşe; Spada, Nicholas J; Fraser, Matthew P; Chellam, Shankararaman

    2014-01-01

    We report the elemental composition, including Rh, Pd, and Pt, of total (i.e., tailpipe and nontailpipe) PM2.5 and PM10 emissions from predominantly gasoline-driven light-duty vehicles (LDVs) traversing the Washburn Tunnel in Houston, Texas during November and December, 2012. Using a novel sample preparation and dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry technique, we quantify the emission of numerous representative, transition, and lanthanoid elements. Two sets of time integrated PM samples were collected over 3-4week duration both inside the tunnel as well as from the tunnel ventilation air supply to derive accurate LDV source profiles incorporating three platinum group elements (PGEs) for the first time. Average Rh, Pd, and Pt concentrations from the tunnel ventilation air supply were 1.5, 11.1, and 4.5pgm(-3) in PM2.5 and 3.8, 23.1, and 15.1pgm(-3) in PM10, respectively. Rh, Pd, and Pt levels were elevated inside the Washburn Tunnel reaching 12.5, 91.1, and 30.1pgm(-3) in PM2.5 and 36.3, 214, and 61.1pgm(-3) in PM10, respectively. Significantly higher enrichment factors of Cu, Zr, Rh, Pd, Sb, and Pt (referenced to Ti in the upper continental crust) inside the tunnel compared with the ventilation air supply suggested that they are unique elemental tracers of PM derived from gasoline-driven LDVs. This highlights the importance of advancing methods to quantify the trace level PGE emissions as a technique to more accurately estimate LDVs' contributions to airborne PM. Using the emission profile based on PGEs and ambient quantification, mass balancing revealed that approximately half the fine PM mass in the tunnel could be attributed to tailpipe emissions, approximately one-quarter to road dust, with smaller contributions from brake (7%) and tire (3%) wear. On the other hand, PM10 mostly originated from resuspended road dust (∼50%), with progressively lower contributions from tailpipe emissions (14%), brake wear (9%), and tire

  10. Role of Hypoxia-Inducible Factor 1, α Subunit and cAMP-Response Element Binding Protein 1 in Synergistic Release of Interleukin 8 by Prostaglandin E2 and Nickel in Lung Fibroblasts

    PubMed Central

    Fabisiak, James P.

    2013-01-01

    Numerous epidemiological studies have linked exposure to particulate matter (PM) air pollution with acute respiratory infection and chronic respiratory and cardiovascular diseases. We have previously shown that soluble nickel (Ni), a common component of PM, alters the release of CXC chemokines from cultured human lung fibroblasts (HLF) in response to microbial stimuli via a pathway dependent on disrupted prostaglandin (PG)E2 signaling. The current study sought to identify the molecular events underlying Ni-induced alterations in PGE2 signaling and its effects on IL-8 production. PGE2 synergistically enhances Ni-induced IL-8 release from HLF in a concentration-dependent manner. The effects of PGE2 were mimicked by butaprost and PGE1-alcohol and inhibited with antagonists AH6809 and L-161,982, indicating PGE2 signals via PGE2 receptors 2 and 4. PGE2 and forskolin stimulated cAMP, but it was only in the presence of Ni-induced hypoxia-inducible factor 1, α subunit (HIF1A) that these agents stimulated IL-8 release. The Ni-induced HIF1A DNA binding was enhanced by PGE2 and mediated, in part, by activation of p38 MAPK. Negation of cAMP-response element binding protein 1 or HIF1A using short interfering RNA blocked the synergistic interactions between Ni and PGE2. The results of the current study provide novel information on the ability of atmospheric hypoxia-mimetic metals to disrupt the release of immune-modulating chemokines by HLF in response to PGE2. Moreover, in the presence of HIF1A, cAMP-mediated signaling pathways may be altered to exacerbate inflammatory-like processes in lung tissue, imparting a susceptibility of PM-exposed populations to adverse respiratory health effects. PMID:23526216

  11. Effect of passivation on the dissolution behavior of Ti6A14V and vacuum-brazed Ti6A14V in Hank's ethylene diamine tetra-acetic acid solution Part I Ion release.

    PubMed

    Lee, T M; Chang, E; Yang, C Y

    1999-09-01

    This work aims to investigate the effects of three factors, namely: (1) two differently prepared materials (as-polished Ti6A14V and 2 h brazed Ti6A14V); (2) three different surface passivation treatments (34% nitric acid passivation, 400 degrees C heated in air, and aged in 100 degrees C de-ionized water); and (3) periods of immersion time (up to 32 days), on trace element release in Hank's ethylene diamine tetra-acetic acid (EDTA) solution. After passivation and autoclaving treatment, the specimens were immersed in 8.0 mM EDTA in Hank's solution and maintained at 37 degrees C for periods of time up to 32 days. The 400 degrees C -treated specimens exhibit a substantial reduction in constituent release, which may be attributed to the higher thickness and rutile structure of the surface oxides. For acid-passivated and water-aged treatments, a highly significant decrease in the trace levels of Ti, A1, and V is detected from the brazed Ti6A14V compared to those obtained from the Ti6A14V specimens. It is hypothesized that an anatase-rutile transformation of surface TiO_2 is likely to occur, accelerated by the elements of copper and nickel in the brazed specimens. In addition, a significant time-related decrease in constituent release rate is observed for all kinds of specimens throughout the 0-8 day experimental period. The implication of the results is discussed.

  12. Oxidative calcium release from catechol.

    PubMed

    Riley, Patrick A; Stratford, Michael R L

    2015-04-01

    Oxidation of 4-methylcatechol previously exposed to aqueous calcium chloride was shown by ion chromatography to be associated with release of calcium ions. The catechol was oxidised to the corresponding orthoquinone by the use of tyrosinase from Agaricus bisporus. The oxidative release of calcium from the catechol is ascribed to the diminution of the available hydroxyl functions able to act as chelating groups. Our results suggest that the redox status of melanin may regulate calcium binding and influence calcium levels in pigmented cells.

  13. Oxidative mobilization of cerium and uranium and enhanced release of "immobile" high field strength elements from igneous rocks in the presence of the biogenic siderophore desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Kraemer, Dennis; Kopf, Sebastian; Bau, Michael

    2015-09-01

    Polyvalent trace elements such as the high field strength elements (HFSE) are commonly considered rather immobile during low-temperature water-rock interaction. Hence, they have become diagnostic tools that are widely applied in geochemical studies. We present results of batch leaching experiments focused on the mobilization of certain HFSE (Y, Zr, Hf, Th, U and rare earth elements) from mafic, intermediate and felsic igneous rocks in the presence and absence, respectively, of the siderophore desferrioxamine B (DFOB). Our data show that DFOB strongly enhances the mobility of these trace elements during low-temperature water-rock interaction. The presence of DFOB produces two distinct features in the Rare Earths and Yttrium (REY) patterns of leaching solutions, regardless of the mineralogical and chemical composition or the texture of the rock type studied. Bulk rock-normalized REY patterns of leaching solutions with DFOB show (i) a very distinct positive Ce anomaly and (ii) depletion of La and other light REY relative to the middle REY, with a concave downward pattern between La and Sm. These features are not observed in experiments with hydrochloric acid, acetic acid or deionized water. In DFOB-bearing leaching solutions Ce and U are decoupled from and selectively enriched relative to light REY and Th, respectively, due to oxidation to Ce(IV) and U(VI). Oxidation of Ce3+ and U4+ is promoted by the significantly higher stability of the Ce(IV) and U(VI) DFOB complexes as compared to the Ce(III) and U(IV) DFOB complexes. This is similar to the relationship between the Ce(IV)- and Ce(III)-pentacarbonate complexes that cause positive Ce anomalies in alkaline lakes. However, while formation of Ce(IV) carbonate complexes is confined to alkaline environments, Ce(IV) DFOB complexes may produce positive Ce anomalies even in mildly acidic and near-neutral natural waters. Siderophore-promoted dissolution processes also significantly enhance mobility of other 'immobile' HFSE

  14. Effect of weathering on abundance and release of potentially toxic elements in soils developed on Lower Cambrian black shales, P. R. China.

    PubMed

    Yu, Changxun; Peng, Bo; Peltola, Pasi; Tang, Xiaoyan; Xie, Shurong

    2012-06-01

    This paper examines the geochemical features of 8 soil profiles developed on metalliferous black shales distributed in the central parts of the South China black shale horizon. The concentrations of 21 trace elements and 8 major elements were determined using ICP-MS and XRF, respectively, and weathering intensity (W) was calculated according to a new technique recently proposed in the literature. The data showed that the black shale soils inherited a heterogeneous geochemical character from their parent materials. A partial least square regression model and EF(bedrock) (enrichment factor normalized to underlying bedrock) indicated that W was not a major control in the redistribution of trace metals. Barium, Sn, Cu, V, and U tended to be leached in the upper soil horizons and trapped by Al and Fe oxides, whereas Sb, Cd, and Mo with negative EF values across the whole profiles may have been leached out during the first stage of pedogenesis (mainly weathering of black shale). Compared with the Chinese average soils, the soils were strongly enriched in the potentially toxic metals Mo, Cd, Sb, Sn, U, V, Cu, and Ba, among which the 5 first listed were enriched to the highest degrees. Elevated concentrations of these toxic metals can have a long-term negative effect on human health, in particular, the soils in mining areas dominated by strongly acidic conditions. As a whole, the black shale soils have much in common with acid sulfate soils. Therefore, black shale soils together with acid sulfate soils deserve more attention in the context of metal exposure and human health.

  15. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres.

    PubMed

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-25

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al(+) regardless of the background gas species, whereas Cr(2+) ions were dominating in Ar and N2 and Cr(+) in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.

  16. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres

    PubMed Central

    Franz, Robert; Polcik, Peter; Anders, André

    2015-01-01

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings. PMID:26120236

  17. Metal DiCarbides as Intermediate Species in thermal Ion Formation Mechanisms

    SciTech Connect

    Matthew G. Watrous; James E. Delmore

    2009-09-01

    The lanthanide elements (lanthanum to lutetium) adsorbed onto resin beads have been studied as thermal ionization sources. Temperatures at which these ion sources gave maximum intensities were measured for each of these elements. The temperature trends track the trends in the dissociation energies of the corresponding metal dicarbide compounds. The metal dicarbide functions as a carrier to take the lanthanide element to higher temperatures than otherwise attainable. This results in the release of the atomic species at a higher temperature where the ionization probability is significantly increased. This breaking of molecular bonds releasing the atoms at these elevated temperatures is hypothesized as the reason for high ionization efficiencies.

  18. Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum

    PubMed Central

    Loy, Ryan E.; Orynbayev, Murat; Xu, Le; Andronache, Zoita; Apostol, Simona; Zvaritch, Elena; MacLennan, David H.; Meissner, Gerhard; Melzer, Werner

    2011-01-01

    The type 1 isoform of the ryanodine receptor (RYR1) is the Ca2+ release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation–contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1I4898T mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca2+ content, and RYR1 Ca2+ release channel function using adult heterozygous Ryr1I4895T/+ knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca2+ content, both electrically evoked and 4-chloro-m-cresol–induced Ca2+ release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4–6-mo-old IT/+ mice. The sensitivity of the SR Ca2+ release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca2+ permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca2+ release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca2+ ion permeation. PMID:21149547

  19. Muscle weakness in Ryr1I4895T/WT knock-in mice as a result of reduced ryanodine receptor Ca2+ ion permeation and release from the sarcoplasmic reticulum.

    PubMed

    Loy, Ryan E; Orynbayev, Murat; Xu, Le; Andronache, Zoita; Apostol, Simona; Zvaritch, Elena; MacLennan, David H; Meissner, Gerhard; Melzer, Werner; Dirksen, Robert T

    2011-01-01

    The type 1 isoform of the ryanodine receptor (RYR1) is the Ca(2+) release channel of the sarcoplasmic reticulum (SR) that is activated during skeletal muscle excitation-contraction (EC) coupling. Mutations in the RYR1 gene cause several rare inherited skeletal muscle disorders, including malignant hyperthermia and central core disease (CCD). The human RYR1(I4898T) mutation is one of the most common CCD mutations. To elucidate the mechanism by which RYR1 function is altered by this mutation, we characterized in vivo muscle strength, EC coupling, SR Ca(2+) content, and RYR1 Ca(2+) release channel function using adult heterozygous Ryr1(I4895T/+) knock-in mice (IT/+). Compared with age-matched wild-type (WT) mice, IT/+ mice exhibited significantly reduced upper body and grip strength. In spite of normal total SR Ca(2+) content, both electrically evoked and 4-chloro-m-cresol-induced Ca(2+) release were significantly reduced and slowed in single intact flexor digitorum brevis fibers isolated from 4-6-mo-old IT/+ mice. The sensitivity of the SR Ca(2+) release mechanism to activation was not enhanced in fibers of IT/+ mice. Single-channel measurements of purified recombinant channels incorporated in planar lipid bilayers revealed that Ca(2+) permeation was abolished for homotetrameric IT channels and significantly reduced for heterotetrameric WT:IT channels. Collectively, these findings indicate that in vivo muscle weakness observed in IT/+ knock-in mice arises from a reduction in the magnitude and rate of RYR1 Ca(2+) release during EC coupling that results from the mutation producing a dominant-negative suppression of RYR1 channel Ca(2+) ion permeation.

  20. Three-dimensional finite-element model of the ion Bernstein wave antenna and excitation of coaxial electrostatic edge modes in the tokamak fusion test reactor

    NASA Astrophysics Data System (ADS)

    Intrator, T.; Myra, J. R.; D'Ippolito, D. A.

    2003-07-01

    Externally launched ion Bernstein wave (IBW) experiments have demonstrated localized electron heating, sheared flows and transport barriers in several tokamaks. Experiments in the tokamak fusion test reactor (TFTR) showed that IBW waves launched from low-field side IBW antennas could drive a velocity shear layer in the central plasma, but the power coupled to the IBW was not sufficient to achieve a transport barrier. This experiment raised important questions concerning where the radio-frequency (rf) power went and whether the anomalous loss channels are more important in larger machines. Recently, it was proposed that the power loss was due to a coaxial electron plasma wave (EPW) mode excited in the low density plasma halo near the vessel wall (Myra et al 2000 Phys. Plasmas 7 283). This mode could dissipate a significant power fraction by sheath and collisional mechanisms, fits more easily in larger machines like TFTR and has the phasing dependence observed in the experiments. Here we extend that work by demonstrating the existence and phasing dependence of the coaxial mode (CM) in a realistic rf coupling calculation. A three-dimensional finite-element electromagnetic code couples a detailed model of the antenna geometry with a plasma dielectric model that retains CM physics. Quantitative results show the dependence of the CM rf fields and power dissipation on the phasing of the multiple-strap array. Unlike conventional rf coupling codes, this paper enables the antenna limiters to be immersed in tenuous plasma, an important feature for correctly modelling parasitic coupling to the CM.

  1. Ion colliders

    SciTech Connect

    Fischer, W.

    2011-12-01

    RHIC and LHC injector chains for the heaviest ion species used to date. The RHIC pulsed sputter source (PSC) and Tandem electrostatic accelerator are being replaced by an Electron Beam Ion Source (EBIS), Radio Frequency Quadrupole (RFQ) and short linac [08Ale1]. With EBIS beams of any element can be prepared for RHIC including uranium and spin-polarized 3He. At CERN an ECR ion source is used, followed by an RFQ and Linac. The ions are then accumulated, electron cooled, and accelerated in LEIR. After transfer to and acceleration in the PS, ion beams are injected into the SPS.

  2. Performance of SONY 18650-HC Lithium-Ion Cells for Various Cycling Rates

    DTIC Science & Technology

    2010-01-15

    AEROSPACE REPORT NO. TR-2010(8550)-5 Performance of SONY 18650 -HC Lithium-Ion Cells for Various Cycling Rates 15 January 2010 Albert H...SONY 18650 -HC Lithium-Ion Cells for Various Cycling Rates 5a. CONTRACT NUMBER FA8802-09-C-0001 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6...Approved for public release; distribution unlimited. 13. SUPPLEMENTARY NOTES 20100310195 14. ABSTRACT Five different life tests of SONY 18650 -HC lithium

  3. Negative ion generator

    DOEpatents

    Stinnett, Regan W.

    1984-01-01

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions.

  4. Negative ion generator

    DOEpatents

    Stinnett, R.W.

    1984-05-08

    A negative ion generator is formed from a magnetically insulated transmission line having a coating of graphite on the cathode for producing negative ions and a plurality of apertures on the opposed anode for the release of negative ions. Magnetic insulation keeps electrons from flowing from the cathode to the anode. A transverse magnetic field removes electrons which do escape through the apertures from the trajectory of the negative ions. 8 figs.

  5. Charge exchange molecular ion source

    DOEpatents

    Vella, Michael C.

    2003-06-03

    Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

  6. Ba2+ release from soda glass modifies single maxi K+ channel activity in patch clamp experiments.

    PubMed Central

    Copello, J; Simon, B; Segal, Y; Wehner, F; Ramanujam, V M; Alcock, N; Reuss, L

    1991-01-01

    Glasses used to fabricate patch pipettes may release components which affect ion channels (Cota, G., and C.M. Armstrong. 1988. Biophys. J. 53:107-109; Furman, R.E., and J.C. Tanaka. 1988. Biophys. J. 53:287-292; Rojas, L., and C. Zuazaga. 1988. Neurosci. Lett. 88:39-44). The gating properties of maxi K+ channels from Necturus gallbladder epithelium depend on whether borosilicate glass (BG) or blue tip hematocrit glass (SG) is used to construct the patch pipettes. The data are consistent with solubilization from SG of a component which exerts voltage-dependent, cytosolic-side specific block, closely resembling "slow block" by Ba2+ ions. Ringer's solution preincubated with SG, but not with BG, blocked inside-out maxi K+ channels when used as bathing solution. Mass spectrometry revealed that Ba2+ is released by the glass from fast and slow-release compartments (SG contains 3% wt/wt BaO), and is the only ion found in the solution at concentrations consistent with the observed channel block. Additionally, SG released O2-, Na+, Ca2+, and Mg2+, all to micromolar concentrations. These elements do not interfere with maxi K+ channels but they could in principle alter the properties of other ion channels. Thus, screening for channel-modifying substances released by the glass may be necessary for the adequate interpretation of patch-clamp results. PMID:1742460

  7. Experimental study and modeling of the deuterium releasing quantity in a pulsed vacuum arc discharge with a metal deuteride cathode

    NASA Astrophysics Data System (ADS)

    Liu, Fei-Xiang; Long, Ji-Dong; Zheng, Le; Dong, Pan; Li, Chen; Chen, Wei

    2017-04-01

    The pulsed vacuum arc discharge using a metal deuteride cathode is widely applied as a deuterium ion source, where the upper limit of the deuterium ion yield is largely determined by the deuterium releasing quantity (DRQ) from the cathode. This work aims to measure the DRQ at various discharge conditions, and meanwhile develop a simple thermoelectric model to evaluate the deuterium liberation from different sources, such as the crater vicinity during the arc power-on phase and the hot crater in the afterglow. The calculated DRQ are in accordance with the experimental results obtained by measuring the D2 pressure evolution in the early afterglow using a quadrupole mass spectrometer. Furthermore, the model reveals that at low arc current (<10 A), the DRQ orginates dominantly from the crater vicinity, leading to a low conversion efficiency of the released deuterium to ions and a high D:Ti elemental ratio in the released cathode vapor.

  8. Ca(2+)-activated ion currents triggered by ryanodine receptor-mediated Ca(2+) release control firing of inhibitory neurons in the prepositus hypoglossi nucleus.

    PubMed

    Saito, Yasuhiko; Yanagawa, Yuchio

    2013-01-01

    Spontaneous miniature outward currents (SMOCs) are known to exist in smooth muscles and peripheral neurons, and evidence for the presence of SMOCs in central neurons has been accumulating. SMOCs in central neurons are induced through Ca(2+)-activated K(+) (K(Ca)) channels, which are activated through Ca(2+)-induced Ca(2+) release from the endoplasmic reticulum via ryanodine receptors (RyRs). Previously, we found that some neurons in the prepositus hypoglossi nucleus (PHN) showed spontaneous outward currents (SOCs). In the present study, we used whole cell recordings in slice preparations of the rat brain stem to investigate the following: 1) the ionic mechanisms of SOCs, 2) the types of neurons exhibiting frequent SOCs, and 3) the effect of Ca(2+)-activated conductance on neuronal firing. Pharmacological analyses revealed that SOCs were induced via the activation of small-conductance-type K(Ca) (SK) channels and RyRs, indicating that SOCs correspond to SMOCs. An analysis of the voltage responses to current pulses of the fluorescence-expressing inhibitory neurons of transgenic rats revealed that inhibitory neurons frequently exhibited SOCs. Abolition of SOCs via blockade of SK channels enhanced the frequency of spontaneous firing of inhibitory PHN neurons. However, abolition of SOCs via blockade of RyRs reduced the firing frequency and hyperpolarized the membrane potential. Similar reductions in firing frequency and hyperpolarization were also observed when Ca(2+)-activated nonselective cation (CAN) channels were blocked. These results suggest that, in inhibitory neurons in the PHN, Ca(2+) release via RyRs activates SK and CAN channels, and these channels regulate spontaneous firing in a complementary manner.

  9. EFFECTIVENESS OF NaOCl ALONE OR IN COMBINATION WITH EDTA ON THE DIFFUSION OF HYDROXYL IONS RELEASED BY CALCIUM HYDROXIDE PASTE

    PubMed Central

    FELIPPE, Mara Cristina Santos; FELIPPE, Wilson Tadeu; ESPEZIM, Catherine Schmitz; de FREITAS, Sérgio Fernando Torres

    2006-01-01

    Aim: To evaluate the effect of different irrigant solutions employed during removal and replacement of calcium hydroxide paste on the diffusion of hydroxyl ions through root canal dentine in vitro. Methodology: Thirty-five maxillary and mandibular human canines with straight and fully developed roots were used. After mechanical preparation up to 1mm short of tooth length, 30 canals were filled with calcium hydroxide paste and 5 canals were left empty; all teeth had their coronal accesses properly sealed. Teeth were placed in plastic containers with distilled water, and pH was read after 30 days when the paste from 20 teeth was renewed. After removal of the paste by endodontic instrumentation and irrigation with distilled water, canals were replenished with newly mixed paste in Group 1 and 2. In these groups, final irrigation was conducted with 5 mL of EDTA followed by 5 mL of NaOCl in specimens in Group 1, and 5 mL of NaOCl only in specimens in Group 2. In 10 teeth the paste was not replenished at 30 days (Group 3). All specimens were returned to the containers with fresh distilled water, and the pH was recorded after another 30 days. The differences between the first (30d) and second (60d) pH readings were calculated and submitted to analysis of variance and individual comparisons using the Scheffeé's test. Results: Results of mean analysis on differences of pH readings showed that greater diffusion had occurred on specimens in Group 3. Individual comparisons using Scheffeé's test showed statistical significance between Groups 2 and 3, and equivalence between all other groups. Conclusion: It was concluded that the use of EDTA did not enhance diffusion of hydroxyl ions through root canal dentine. PMID:19089021

  10. Influence of Nitinol wire surface treatment on oxide thickness and composition and its subsequent effect on corrosion resistance and nickel ion release.

    PubMed

    Clarke, B; Carroll, W; Rochev, Y; Hynes, M; Bradley, D; Plumley, D

    2006-10-01

    Medical implants and devices are now used successfully in surgical procedures on a daily basis. Alloys of nickel and titanium, and in particular Nitinol are of special interest in the medical device industry, because of their shape memory and superelastic properties. The corrosion behavior of nitinol in the body is also of critical importance because of the known toxicological effects of nickel. The stability of a NiTi alloy in the physiological environment is dependant primarily on the properties of the mostly TiO(2) oxide layer that is present on the surface. For the present study, a range of nitinol wires have been prepared using different drawing processes and a range of surface preparation procedures. It is clear from the results obtained that the wire samples with very thick oxides also contain a high nickel content in the oxide layer. The untreated samples with the thicker oxides show the lowest pitting potential values and greater nickel release in both long and short-term experiments. It was also found that after long-term immersion tests breakdown potentials increased for samples that exhibited lower values initially. From these results it would appear that surface treatment is essential for the optimum bioperformance of nitinol.

  11. Statistical analysis of major ion and trace element geochemistry of water, 1986-2006, at seven wells transecting the freshwater/saline-water interface of the Edwards Aquifer, San Antonio, Texas

    USGS Publications Warehouse

    Mahler, Barbara J.

    2008-01-01

    The statistical analyses taken together indicate that the geochemistry at the freshwater-zone wells is more variable than that at the transition-zone wells. The geochemical variability at the freshwater-zone wells might result from dilution of ground water by meteoric water. This is indicated by relatively constant major ion molar ratios; a preponderance of positive correlations between SC, major ions, and trace elements; and a principal components analysis in which the major ions are strongly loaded on the first principal component. Much of the variability at three of the four transition-zone wells might result from the use of different laboratory analytical methods or reporting procedures during the period of sampling. This is reflected by a lack of correlation between SC and major ion concentrations at the transition-zone wells and by a principal components analysis in which the variability is fairly evenly distributed across several principal components. The statistical analyses further indicate that, although the transition-zone wells are less well connected to surficial hydrologic conditions than the freshwater-zone wells, there is some connection but the response time is longer. 

  12. Toxicological risk assessment of elemental gold following oral exposure to sheets and nanoparticles - A review.

    PubMed

    Hadrup, Niels; Sharma, Anoop K; Poulsen, Morten; Nielsen, Elsa

    2015-07-01

    Elemental gold is used as a food coloring agent and in dental fillings. In addition, gold nanoparticles are gaining increasing attention due to their potential use as inert carriers for medical purposes. Although elemental gold is considered to be inert, there is evidence to suggest the release of gold ions from its surface. Elemental gold, or the released ions, is, to some extent, absorbed in the gastrointestinal tract. Gold is distributed to organs such as the liver, heart, kidneys and lungs. The main excretion route of absorbed gold is through urine. Data on the oral toxicity of elemental gold is limited. The acute toxicity of elemental gold seems to be low, as rats were unaffected by a single dose of 2000mg nanoparticles/kg of body weight. Information on repeated dose toxicity is very limited. Skin rashes have been reported in humans following the ingestion of liquors containing gold. In addition, gold released from dental restorations has been reported to increase the risk of developing gold hypersensitivity. Regarding genotoxicity, in vitro studies indicate that gold nanoparticles induce DNA damage in mammalian cells. In vivo, gold nanoparticles induce genotoxic effects in Drosophila melanogaster; however, genotoxicity studies in mammals are lacking. Overall, based on the literature and taking low human exposure into account, elemental gold via the oral route is not considered to pose a health concern to humans in general.

  13. Rare earth element selenochemistry of immiscible liquids and zircon at Apollo 14 - An ion probe study of evolved rocks on the moon

    NASA Technical Reports Server (NTRS)

    Snyder, Gregory A.; Taylor, Lawrence A.; Crozaz, Ghislaine

    1993-01-01

    Results are presented of trace-element analyses of three lunar zircons. The major-element and REE compositions were determined using electron microprobes, and a correction was made for zircon for Zr-Si-O molecular interferences in the La to Pr mass region. The three zircons were found to exhibit similar REE abundances and patterns. Results of the analyses confirm earlier studies (Hess et al., 1975; Watson, 1976; Neal and Taylor, 1989) on the partitioning behavior of trace elements in immiscible liquid-liquid pairs. The results also support the postulated importance of silicate liquid immiscibility in the differentiation of the upper mantle and crust of the moon.

  14. HEAVY ION LINEAR ACCELERATOR

    DOEpatents

    Van Atta, C.M.; Beringer, R.; Smith, L.

    1959-01-01

    A linear accelerator of heavy ions is described. The basic contributions of the invention consist of a method and apparatus for obtaining high energy particles of an element with an increased charge-to-mass ratio. The method comprises the steps of ionizing the atoms of an element, accelerating the resultant ions to an energy substantially equal to one Mev per nucleon, stripping orbital electrons from the accelerated ions by passing the ions through a curtain of elemental vapor disposed transversely of the path of the ions to provide a second charge-to-mass ratio, and finally accelerating the resultant stripped ions to a final energy of at least ten Mev per nucleon.

  15. Synchrotron X-Ray Fluorescence Analysis of Trace Elements in Focused Ion Beam Prepared Sections of Carbonaceous Chondrite Iron Sulfides (CM and CR) and Associated Metal (CR)

    NASA Astrophysics Data System (ADS)

    Singerling, S. A.; Sutton, S. R.; Lanzirotti, A.; Newville, M.; Brearley, A. J.

    2016-08-01

    This study presents data on trace element abundances in CM and CR sulfides and metals. We determined that Ge and Zn were observed to be depleted relative to CI chondrite while the more volatile Se was observed to be enriched.

  16. Separation of Bk(IV) and Ce(IV) from trivalent transplutonium and rare-earth elements on ion exchangers in solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Stepushkina, V.V.

    1988-05-01

    The behavior of Am, Cm, Bk, Cf, Es, Ce, Eu, and Pr on anion exchangers and cation exchangers mixed with PbO/sub 2/ in solutions of sulfuric acid has been investigated. A significant difference between the distribution coefficients of Bk and Ce, on the one hand, and the remaining transplutonium elements and rare-earth elements, on the other hand, which has been attributed to the oxidation of the first two elements to the tetravalent state, has been discovered. Methods for the preconcentration and separation of Bk(IV) and Ce(IV) from the other transplutonium and rare-earth element son anion exchangers in 0.01-0.25 M H/sub 2/SO/sub 4/ solutions and on cation exchangers in 0.75-1.0 M H/sub 2/SO/sub 4/ solutions have been proposed.

  17. ION SOURCE

    DOEpatents

    Bell, W.A. Jr.; Love, L.O.; Prater, W.K.

    1958-01-28

    An ion source is presented capable of producing ions of elements which vaporize only at exceedingly high temperatures, i.e.,--1500 degrees to 3000 deg C. The ion source utilizes beams of electrons focused into a first chamber housing the material to be ionized to heat the material and thereby cause it to vaporize. An adjacent second chamber receives the vaporized material through an interconnecting passage, and ionization of the vaporized material occurs in this chamber. The ionization action is produced by an arc discharge sustained between a second clectron emitting filament and the walls of the chamber which are at different potentials. The resultant ionized material egresses from a passageway in the second chamber. Using this device, materials which in the past could not be processed in mass spectometers may be satisfactorily ionized for such applications.

  18. Determination of selected elements in whole coal and in coal ash from the eight argonne premium coal samples by atomic absorption spectrometry, atomic emission spectrometry, and ion-selective electrode

    USGS Publications Warehouse

    Doughten, M.W.; Gillison, J.R.

    1990-01-01

    Methods for the determination of 24 elements in whole coal and coal ash by inductively coupled argon plasma-atomic emission spectrometry, flame, graphite furnace, and cold vapor atomic absorption spectrometry, and by ion-selective electrode are described. Coal ashes were analyzed in triplicate to determine the precision of the methods. Results of the analyses of NBS Standard Reference Materials 1633, 1633a, 1632a, and 1635 are reported. Accuracy of the methods is determined by comparison of the analysis of standard reference materials to their certified values as well as other values in the literature.

  19. Metal release in metallothioneins induced by nitric oxide: X-ray absorption spectroscopy study.

    PubMed

    Casero, Elena; Martín-Gago, José A; Pariente, Félix; Lorenzo, Encarnación

    2004-12-01

    Metallothioneins (MTs) are low molecular weight proteins that include metal ions in thiolate clusters. The capability of metallothioneins to bind different metals has suggested their use as biosensors for different elements. We study here the interaction of nitric oxide with rat liver MTs by using in situ X-ray absorption spectroscopy techniques. We univocally show that the presence of NO induces the release of Zn atoms from the MT structure to the solution. Zn ions transform in the presence of NO from a tetrahedral four-fold coordinated environment in the MT into a regular octahedral six-fold coordinated state, with interatomic distances compatible with those of Zn solvated in water.

  20. Propensity-matched patient-level comparison of the TAXUS Liberté and TAXUS element (ION) paclitaxel-eluting stents.

    PubMed

    Kereiakes, Dean J; Cannon, Louis A; Ormiston, John A; Turco, Mark A; Mann, Tift; Mishkel, Gregory J; McGarry, Thomas; Wang, Hong; Underwood, Paul; Dawkins, Keith D

    2011-09-15

    Stent design, metal alloy composition, and strut thickness may influence late lumen loss and clinical outcomes after bare metal stent deployment; however, their impact on outcomes after drug-eluting stent deployment is unknown. Although the TAXUS Liberté and ION paclitaxel-eluting stents use similar polymer and drug, the ION stent incorporates a novel thin-strut platinum chromium metal alloy and cell design. We therefore compared patient-level data from 2,298 subjects enrolled into the TAXUS ATLAS (TAXUS Liberté) and PERSEUS (ION) clinical trials. Propensity-score (1:1) matching was performed to adjust for covariate imbalance between stent types. Twelve-month major adverse cardiac events were less frequent after use of the ION compared to the TAXUS Liberté (12.7% vs 8.3%, p <0.001, unadjusted; 12.0% vs 7.5%, p = 0.007, propensity matched) largely because of decreased non-Q-wave myocardial infarction (MI; 2.9% vs 1.4%, p = 0.01, unadjusted; 3.2% vs 0.9%, p = 0.004, propensity matched). The MI difference was predominantly periprocedural and in patients treated with a single stent. In conclusion, this exploratory post hoc analysis demonstrated that the ION was associated with fewer adverse clinical events than the TAXUS Liberté because of decreased non-Q-wave MI. Stent platform-related variables may influence clinical outcomes after drug-eluting stent use despite similar polymer and drug elution. Differences in adjunctive pharmacotherapy and/or stenting technique may also be contributory.

  1. High temperature ion source for an on-line isotope separator

    DOEpatents

    Mlekodaj, Ronald L.

    1979-01-01

    A reduced size ion source for on-line use with a cyclotron heavy-ion beam is provided. A sixfold reduction in source volume while operating with similar input power levels results in a 2000.degree. C. operating temperature. A combined target/window normally provides the reaction products for ionization while isolating the ion source plasma from the cyclotron beam line vacuum. A graphite felt catcher stops the recoiling reaction products and releases them into the plasma through diffusion and evaporation. Other target arrangements are also possible. A twenty-four hour lifetime of unattended operation is achieved, and a wider range of elements can be studied than was heretofore possible.

  2. Elemental characterization of commercial mate tea leaves (Ilex paraguariensis A. St.-Hil.) before and after hot water infusion using ion beam techniques.

    PubMed

    Giulian, Raquel; Santos, Carla Eliete Iochims dos; Shubeita, Samir de Moraes; Silva, Luiza Manfredi da; Dias, Johnny Ferraz; Yoneama, Maria Lúcia

    2007-02-07

    Ilex paraguariensis A. St.-Hil. is used to prepare a traditional tealike beverage widely appreciated in Argentina, Paraguay, Uruguay, and southern Brazil. In these countries, the tea is popularly known as mate or chimarrão. The aim of this work is to characterize the elemental composition of commercial Ilex paraguariensis and determine the portion of each element present in the leaves that is eluted in the water during the infusion process and consequently ingested by the drinker. Using the particle-induced X-ray emission technique, we verified the presence of Mg, Al, Si, P, S, Cl, K, Ca, Ti, Mn, Fe, Cu, Zn, and Rb at different concentrations, which accounts for about 3.4% of the total mass. The results show a loss of about 90% of K and Cl, 50% of Mg and P, and 20% of Mn, Fe, Cu, Zn, and Rb by the leaves after the infusion. The volume of water used in the infusion affects only the concentration of elements such as Cl, P, K, and Mg until the first 600 mL of water, where a steep decrease in the concentration of these elements was observed in brewed leaves. Furthermore, higher water temperatures (typical temperatures used in infusions, between 80 and 100 degrees C) favor the extraction of K and Cl into the infusion, while the concentration of other elements remains practically constant as a function of temperature.

  3. Separation of Bk(IV) and Ce(IV) from trivalent transplutonium and rare earth elements on ion exchange resins in solutions of sulfuric acid

    SciTech Connect

    Guseva, L.I.; Stepushkina, V.V.

    1987-11-01

    Th behavior of Am, Cm, Bk, Cf, Es, Ce, Eu, and Pr on an anion exchange resin and a cation exchange resin in a mixture with PbO/sub 2/ was investigated in sulfuric acid solutions. A substantial difference was detected in the distribution coefficients of Bk and Ce, on the one hand, and the remaining transplutonium and rare earth elements, on the other, associated with oxidation of the first two elements to the tetravalent state. Methods are proposed for the concentration and separation of Bk(IV) and Ce(IV) from the other transplutonium and rare earth elements on an anion exchange resin in solution of 0.01-0.25 M H/sub 2/SO/sub 4/ and a cation exchange resin in 0.75-1.0 M H/sub 2/SO/sub 4/.

  4. Areal distribution of selected trace elements, salinity, and major ions in shallow ground water, Tulare Basin, Southern San Joaquin Valley, California

    USGS Publications Warehouse

    Fujii, Roger; Swain, W.C.

    1995-01-01

    The distribution of salinity and selected trace elements in shallow ground water in the Tulare Basin, California, was assessed to evaluate potential problems related to disposal in evaporation ponds of irrigation drain water containing elevated concentrations of selenium and other trace elements. The constituents of primary concern were selenium, arsenic, and salinity; uranium, boron, and molybdenum also were evaluated. Samples from 117 shallow wells were analyzed, and the results for samples from 110 of the wells were interpreted in relation to surficial geology, sediment depositional environment, soil characteristics, and hydrologic processes to determine the geochemical and hydrologic factors affecting the distribution of these constituents in ground water. In general, shallow ground water in areas where concentrations of salinity and most trace elements are elevated is influenced primarily by sediments derived from marine sedimentary rocks originating in the Coast Range, San Emigdio Mountains, and Tehachapi Mountains, and probably by unusual exposures of similar marine formations in the Sierra Nevada. Ground water in areas where concentrations of salinity and trace elements are significantly lower generally is influenced by igneous and metamorphic rocks exposed in the Sierra Nevada. In addition to sources of sediments, evaporation of shallow ground water, as indicated by isotopic enrichment of oxygen-18 and deuterium, increases salinity and concentrations of conservative trace elements such as selenium (under oxidizing conditions) and boron. Redox conditions affect the oxidation state of all trace elements of concern, except boron, and were found to be a major influence on trace-element solubility. Under oxidized conditions, selenate predominates and behaves conservatively, and arsenate predominates and is affected by sorption reactions that can limit arsenic solubility. Under reduced conditions, selenium is reduced to insoluble elemental selenium and arsenite

  5. Numerical simulations of gas mixing effect in electron cyclotron resonance ion sources

    NASA Astrophysics Data System (ADS)

    Mironov, V.; Bogomolov, S.; Bondarchenko, A.; Efremov, A.; Loginov, V.

    2017-01-01

    The particle-in-cell Monte Carlo collisions code nam-ecris is used to simulate the electron cyclotron resonance ion source (ECRIS) plasma sustained in a mixture of Kr with O2 , N2 , Ar, Ne, and He. The model assumes that ions are electrostatically confined in the ECR zone by a dip in the plasma potential. A gain in the extracted krypton ion currents is seen for the highest charge states; the gain is maximized when oxygen is used as a mixing gas. The special feature of oxygen is that most of the singly charged oxygen ions are produced after the dissociative ionization of oxygen molecules with a large kinetic energy release of around 5 eV per ion. The increased loss rate of energetic lowly charged ions of the mixing element requires a building up of the retarding potential barrier close to the ECR surface to equilibrate electron and ion losses out of the plasma. In the mixed plasmas, the barrier value is large (˜1 V ) compared to pure Kr plasma (˜0.01 V ), with longer confinement times of krypton ions and with much higher ion temperatures. The temperature of the krypton ions is increased because of extra heating by the energetic oxygen ions and a longer time of ion confinement. In calculations, a drop of the highly charged ion currents of lighter elements is observed when adding small fluxes of krypton into the source. This drop is caused by the accumulation of the krypton ions inside plasma, which decreases the electron and ion confinement times.

  6. Endothelial responses of magnesium and other alloying elements in magnesium-based stent materials

    PubMed Central

    Zhao, Nan; Zhu, Donghui

    2016-01-01

    Biodegradable tailored magnesium (Mg) alloys are some of the most promising scaffolds for cardiovascular stents. During the course of degradation after implantation, all the alloying elements in the scaffold will be released to the surrounding vascular tissues. However, fundamental questions regarding the toxicity of alloying elements towards vascular cells, the maximum amount of each element that could be used in alloy design, or how each of the alloying elements affects vascular cellular activity and gene expression, are still not fully answered. This work systematically addressed these questions by revealing how application of different alloying elements commonly used in Mg stent materials influences several indices of human endothelial cell health, i.e., viability, proliferations, cytoskeletal reorganizations, migration, and the gene expression profile. The overall cell viability and proliferation showed a decreasing trend with increasing concentrations of the ions, and the half maximal effective concentrations (EC50) for each element were determined. When applied at a low concentration of around 10 mM, Mg had no adverse effects but improved cell proliferation and migration instead. Mg ions also altered endothelial gene expression significantly in a dose dependent manner. Most of the changed genes are related to angiogenesis and the cell adhesion signaling pathways. Findings from this work provide useful information on maximum safe doses of these ions for endothelial cells, endothelial responses towards these metal ions, and some guidance for future Mg stent design. PMID:25363018

  7. Syndactyly Release.

    PubMed

    Braun, Tara L; Trost, Jeffrey G; Pederson, William C

    2016-11-01

    Syndactyly is one of the most common congenital hand anomalies treated by pediatric plastic surgeons. Established principles of syndactyly separation dictate the timing and order of syndactyly release, with the goals of surgery being the creation of an anatomically normal webspace, tension-free closure of soft tissue, and return of function to the fingers. Numerous surgical methods have been described, many of which involve the use of local flaps to reconstruct the commissure and full-thickness skin grafts for coverage of raw areas. Recently, reconstructive techniques without the use of skin grafts have been devised, which work well for certain indications. Special considerations are described for complete, complex, and syndromic syndactylies. Outcomes for simple syndactyly release are typically good when surgical principles are followed, whereas complex syndactyly release tends to have less-favorable outcomes and more complications.

  8. Analysis of Orbital Elements and Atmospheric Activity to Ascertain Possible Presence of an Ion Propulsion Capability Aboard Salyut 7/Cosmos 1686

    DTIC Science & Technology

    1991-12-01

    H Saelliie Vernal equinoxE in of nodes Figure 4. Orbital Elements (Reprinted from (22:58)) 1A , A a :A, E: r V E Figure 5. Eccentric Anomaly...34 Journal of Power and Propulsion, Vol. 5, No. 4: 445-451 (July-August 1989). 21. Tipler , Paul A. Physics. New York: W~brth Publishers, Inc., 1976. 22

  9. Ion optics of RHIC EBIS

    SciTech Connect

    Pikin, A.; Alessi, J.; Beebe, E.; Kponou, A.; Okamura, M.; Raparia, D.; Ritter, J.; Tan, Y.; Kuznetsov, G.

    2011-09-10

    RHIC EBIS has been commissioned to operate as a versatile ion source on RHIC injection facility supplying ion species from He to Au for Booster. Except for light gaseous elements RHIC EBIS employs ion injection from several external primary ion sources. With electrostatic optics fast switching from one ion species to another can be done on a pulse to pulse mode. The design of an ion optical structure and the results of simulations for different ion species are presented. In the choice of optical elements special attention was paid to spherical aberrations for high-current space charge dominated ion beams. The combination of a gridded lens and a magnet lens in LEBT provides flexibility of optical control for a wide range of ion species to satisfy acceptance parameters of RFQ. The results of ion transmission measurements are presented.

  10. Correlations in concentrations, xylem and phloem flows, and partitioning of elements and ions in intact plants. A summary and statistical re-evaluation of modelling experiments in Ricinus communis.

    PubMed

    Peuke, Andreas D

    2010-03-01

    Within the last two decades, a series of papers have dealt with the effects of nutrition and nutrient deficiency, as well as salt stress, on the long-distance transport and partitioning of nutrients in castor bean. Flows in xylem and phloem were modelled according to an empirically-based modelling technique that permits additional quantification of the uptake and incorporation into plant organs. In the present paper these data were statistically re-evaluated, and new correlations are presented. Numerous relationships between different compartments and transport processes for single elements, but also between elements, were detected. These correlations revealed different selectivities for ions in bulk net transport. Generally, increasing chemical concentration gradients for mineral nutrients from the rhizosphere to the root and from the xylem to leaf tissue were observed, while such gradients decreased from root tissue to the xylem and from leaves to the phloem. These studies showed that, for the partitioning of nutrients within a plant, the correlated interactions of uptake, xylem and phloem flow, as well as loading and unloading of solutes from transport systems, are of central importance. For essential nutrients, tight correlations between uptake, xylem and phloem flow, and the resulting partitioning of elements, were observed, which allows the stating of general models. For non-essential ions like Na(+) or Cl(-), a statistically significant dependence of xylem transport on uptake was not detected. The central role of the phloem for adjusting, but also signalling, of nutrition status is discussed, since strong correlations between leaf nutrient concentrations and those in phloem saps were observed. In addition, negative correlations between phloem sap sugar concentration and net-photosynthesis, growth, and uptake of nutrients were demonstrated. The question remains whether this is only a consequence of an insufficient use of carbohydrates in plants or a

  11. Toggle release

    NASA Technical Reports Server (NTRS)

    Graves, Thomas J. (Inventor); Yang, Robert A. (Inventor); Brown, Christopher W. (Inventor)

    1989-01-01

    A pyrotechnic actuated structural release device 10 which is mechanically two fault tolerant for release. The device 10 comprises a fastener plate 11 and fastener body 12, each attachable to a different one of a pair of structures to be joined. The fastener plate 11 and body 12 are fastenable by a toggle 13 supported at one end on the fastener plate and mounted for universal pivotal movement thereon. At its other end which is received in a central opening in the fastener body 12 and adapted for limited pivotal movement therein the toggle 13 is restrained by three retractable latching pins 61 symmetrically disposed in equiangular spacing about the axis of the toggle 13 and positionable in latching engagement with an end fitting on the toggle. Each pin 61 is individually retractable by combustion of a pyrotechnic charge 77, the expanding gases of which are applied to a pressure receiving face 67 on the latch pin 61 to effect its retraction from the toggle. While retraction of all three pins 62 releases the toggle, the fastener is mechanically two fault tolerant since the failure of any single one or pair of the latch pins to retract results in an asymmetrical loading on the toggle and its pivotal movement to effect a release. An annular bolt 18 is mounted on the fastener plate 11 as a support for the socket mounting 30, 37 of the toggle whereby its selective axial movement provides a means for preloading the toggle.

  12. Rapid kinetics of iron responsive element (IRE) RNA/iron regulatory protein 1 and IRE-RNA/eIF4F complexes respond differently to metal ions

    PubMed Central

    Khan, Mateen A.; Ma, Jia; Walden, William E.; Merrick, William C.; Theil, Elizabeth C.; Goss, Dixie J.

    2014-01-01

    Metal ion binding was previously shown to destabilize IRE-RNA/IRP1 equilibria and enhanced IRE-RNA/eIF4F equilibria. In order to understand the relative importance of kinetics and stability, we now report rapid rates of protein/RNA complex assembly and dissociation for two IRE-RNAs with IRP1, and quantitatively different metal ion response kinetics that coincide with the different iron responses in vivo. kon, for FRT IRE-RNA binding to IRP1 was eight times faster than ACO2 IRE-RNA. Mn2+ decreased kon and increased koff for IRP1 binding to both FRT and ACO2 IRE-RNA, with a larger effect for FRT IRE-RNA. In order to further understand IRE-mRNA regulation in terms of kinetics and stability, eIF4F kinetics with FRT IRE-RNA were determined. kon for eIF4F binding to FRT IRE-RNA in the absence of metal ions was 5-times slower than the IRP1 binding to FRT IRE-RNA. Mn2+ increased the association rate for eIF4F binding to FRT IRE-RNA, so that at 50 µM Mn2+ eIF4F bound more than 3-times faster than IRP1. IRP1/IRE-RNA complex has a much shorter life-time than the eIF4F/IRE-RNA complex, which suggests that both rate of assembly and stability of the complexes are important, and that allows this regulatory system to respond rapidly to change in cellular iron. PMID:24728987

  13. Toxic Elements in Soil and Groundwater: Short-Time Study on Electrokinetic Removal of Arsenic in the Presence of other Ions

    PubMed Central

    Leszczynska, Danuta; Ahmad, Hafiz

    2006-01-01

    The electrokinetic technique is an emerging technology presently tested in situ to remove dissolved heavy metals from contaminated groundwater. There is a growing interest for using this system to cleanse clayey soil contaminated by toxic metallic ions. Currently, there are very few available non-destructive treatment methods that could be successfully applied in situ on low permeable type of soil matrix. The main objective of presented study was to validate and possibly enhance the overall efficiency of decontamination by the electrokinetic technique of the low permeable soil polluted by the arsenic in combination with chromium and copper ions. The chosen mixture of ions was imitating leak of pesticide well known as chromate copper arsenate (CCA). The chosen technique is showing a big promise to be used in the future as a portable, easy to install and run on sites with spills or leaks hard to reach otherwise; such as in the dense populated and urbanized areas. Laboratory electrokinetic experiments were designed to understand and possibly manipulate main mechanisms involved during forced migration of ions. All tests were conducted on artificially contaminated kaolinite (low permeable clay soil). Electrokinetic migration was inducted by the low voltage dc current applied through soil column. Series of experiments were designed to assess the efficiency of arsenic-chromium-copper remediation by applying (1) only dc current; and (2) by altering the soil environment. Obtained results showed that arsenic could be successfully removed from the soil in one day (25 hours) span. It was significant time reduction, very important during emergency response. Mass recovered at the end of each test depended on initial condition of soil and type of flushing solution. The best results were obtained, when soil was flushed with either NaOH or NaOCl (total removal efficiency 74.4% and 78.1%, respectively). Direct analysis of remained arsenic in soil after these tests confirmed

  14. Ion Beam Processing.

    DTIC Science & Technology

    1987-03-13

    ure are only those which had the greatest effect . Several features of this periodic chart are worth not- ing: i) some elements improve more than one...from nearly all the groups of the periodic table can have beneficial effects on a given property. iv) Ions which improve properties are highlighted...here, but ions which have deleterious effects may also be implanted which facilitates the study of mechanisms of wear and corrosion. v) Elements to

  15. Two- and three-dimensional van krevelen diagrams: a graphical analysis complementary to the kendrick mass plot for sorting elemental compositions of complex organic mixtures based on ultrahigh-resolution broadband fourier transform ion cyclotron resonance mass measurements.

    PubMed

    Wu, Zhigang; Rodgers, Ryan P; Marshall, Alan G

    2004-05-01

    Ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry has resolved and identified the elemental compositions of over 10000 organic constituents of coal and petroleum crude oil. A plot of Kendrick mass defect versus Kendrick nominal mass sorts compounds into homologous series according to compound class (i.e., numbers of N, O, and S heteroatoms), type (number of rings plus double bonds), and degree of alkylation (number of CH(2) groups), to yield unique elemental assignments from ultrahigh-resolution mass measurements in the 200-900 Da range. Interpretation of such a vast compilation requires a simple (preferably graphical) means to differentiate between complex organic mixtures of different origin or processing. In an extension of the recently revived van Krevelen plot, each elemental composition is projected onto two or three axes according to its H/C, O/C, and/or N/C atomic ratios. The H/C ratio separates compounds according to degree of saturation, whereas O/C or N/C ratios separate according to O and N classes. We show that the three-dimensional van Krevelen diagram can completely separate different classes in pyridine-extracted coal or petroleum samples and can also graphically distinguish fossil fuels according to their nature (coal vs petroleum), maturation (coals of different rank), and processing (the same coal at two stages of liquefaction). The van Krevelen diagram thus appears well suited to amplifying and exposing compositional differences within and between complex organic mixtures.

  16. Calcium release from experimental dental materials.

    PubMed

    Okulus, Zuzanna; Buchwald, Tomasz; Voelkel, Adam

    2016-11-01

    The calcium release from calcium phosphate-containing experimental dental restorative materials was examined. The possible correlation of ion release with initial calcium content, solubility and degree of curing (degree of conversion) of examined materials was also investigated. Calcium release was measured with the use of an ion-selective electrode in an aqueous solution. Solubility was established by the weighing method. Raman spectroscopy was applied for the determination of the degree of conversion, while initial calcium content was examined with the use of energy-dispersive spectroscopy. For examined materials, the amount of calcium released was found to be positively correlated with solubility and initial calcium content. It was also found that the degree of conversion does not affect the ability of these experimental composites to release calcium ions.

  17. Chemical weathering in the plain and peninsular sub-basins of the Ganga: Impact on major ion chemistry and elemental fluxes

    NASA Astrophysics Data System (ADS)

    Rai, Santosh K.; Singh, Sunil K.; Krishnaswami, S.

    2010-04-01

    Concentrations of major ions, Sr and 87Sr/ 86Sr have been measured in the Gomti, the Son and the Yamuna, tributaries of the Ganga draining its peninsular and plain sub-basins to determine their contribution to the water chemistry of the Ganga and silicate and carbonate erosion of the Ganga basin. The results show high concentrations of Na and Sr in the Gomti, the Yamuna and the Ganga (at Varanasi) with much of the Na in excess of Cl. The use of this 'excess Na' (Na∗ = Na riv - Cl riv) a common index of silicate weathering yield values of ˜18 tons km -2 yr -1 for silicate erosion rate (SER) in the Gomti and the Yamuna basins. There are however, indications that part of this Na∗ can be from saline/alkaline soils abundant in their basins, raising questions about its use as a proxy to determine SER of the Ganga plain. Independent estimation of SER based on dissolved Si as a proxy give an average value of ˜5 tons km -2 yr -1 for the peninsular and the plain drainages, several times lower than that derived using Na∗. The major source of uncertainty in this estimate is the potential removal of Si from rivers by biological and chemical processes. The Si based SER and CER (carbonate erosion rate) are also much lower than that in the Himalayan sub-basin of the Ganga. The lower relief, runoff and physical erosion in the peninsular and the plain basins relative to the Himalayan sub-basin and calcite precipitation in them all could be contributing to their lower erosion rates. Budget calculations show that the Yamuna, the Son and Gomti together account for ˜75% Na, 41% Mg and ˜53% Sr and 87Sr of their supply to the Ganga from its major tributaries, with the Yamuna dominating the contribution. The results highlight the important role of the plain and peninsular sub-basins in determining the solute and Sr isotope budgets of the Ganga. The study also shows that the anthropogenic contribution accounts for ⩽10% of the major ion fluxes of the Ganga at Rajmahal during high

  18. Research of the thermal-tension condition and the elemental composition gradient changes of binary systems produced by combined ion-plasma method

    NASA Astrophysics Data System (ADS)

    Blesman, A. I.; Postnikov, D. V.; Polonyankin, D. A.

    2015-04-01

    To increase the life cycle of the constructional steel products working at high temperatures in air environment the combined ion-plasma method of surface modification was elaborated. Using the method described in the paper, constructional steel J24056 samples with different refractory metal coatings such as molybdenum and tantalum and film-thickness up to 10 microns were prepared. The calculations of the temperature distribution and the tension on the depth of the specified sample brand coated steel were performed. The research of oxygen distribution in the surface layer after high temperature annealing in an air atmosphere has been conducted. An estimation model of the oxygen distribution within the grains in a binary steel-coating system is proposed in the paper.

  19. Three-Dimensional Optical Tomography and Correlated Elemental Analysis of Hybrid Perovskite Microstructures: An Insight into Defect-Related Lattice Distortion and Photoinduced Ion Migration.

    PubMed

    Galisteo-López, Juan F; Li, Yuelong; Míguez, Hernán

    2016-12-15

    Organic lead halide perovskites have recently been proposed for applications in light-emitting devices of different sorts. More specifically, regular crystalline microstructures constitute an efficient light source and fulfill the geometrical requirements to act as resonators, giving rise to waveguiding and optical amplification. Herein we show three-dimensional laser scanning confocal tomography studies of different types of methylammonium lead bromide microstructures which have allowed us to dissect their photoemission properties with a precision of 0.036 μm(3). This analysis shows that their spectral emission presents strong spatial variations which can be attributed to defect-related lattice distortions. It is also largely enhanced under light exposure, which triggers the migration of halide ions away from illuminated regions, eventually leading to a strongly anisotropic degradation. Our work points to the need for performing an optical quality test of individual crystallites prior to their use in optoelectronics devices and provides a means to do so.

  20. Material/element-dependent fluorescence-yield modes on soft X-ray absorption spectroscopy of cathode materials for Li-ion batteries

    DOE PAGES

    Asakura, Daisuke; Hosono, Eiji; Nanba, Yusuke; ...

    2016-03-07

    Here, we evaluate the utilities of fluorescence-yield (FY) modes in soft X-ray absorption spectroscopy (XAS) of several cathodematerials for Li-ion batteries. In the case of total-FY (TFY) XAS for LiNi0.5Mn1.5O4, the line shape of the Mn L3-edge XAS was largely distorted by the self-absorption and saturation effects, while the distortions were less pronounced at the NiL3 edge. The distortions were suppressed for the inverse-partial-FY (IPFY) spectra. We found that, in the cathodematerials, the IPFY XAS is highly effective for the Cr, Mn, and Fe L edges and the TFY and PFY modes are useful enough for the NiL edge whichmore » is far from the O K edge.« less

  1. Material/element-dependent fluorescence-yield modes on soft X-ray absorption spectroscopy of cathode materials for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Asakura, Daisuke; Hosono, Eiji; Nanba, Yusuke; Zhou, Haoshen; Okabayashi, Jun; Ban, Chunmei; Glans, Per-Anders; Guo, Jinghua; Mizokawa, Takashi; Chen, Gang; Achkar, Andrew J.; Hawthron, David G.; Regier, Thomas Z.; Wadati, Hiroki

    2016-03-01

    We evaluate the utilities of fluorescence-yield (FY) modes in soft X-ray absorption spectroscopy (XAS) of several cathode materials for Li-ion batteries. In the case of total-FY (TFY) XAS for LiNi0.5Mn1.5O4, the line shape of the Mn L3-edge XAS was largely distorted by the self-absorption and saturation effects, while the distortions were less pronounced at the Ni L3 edge. The distortions were suppressed for the inverse-partial-FY (IPFY) spectra. We found that, in the cathode materials, the IPFY XAS is highly effective for the Cr, Mn, and Fe L edges and the TFY and PFY modes are useful enough for the Ni L edge which is far from the O K edge.

  2. Multi-source ion funnel

    DOEpatents

    Tang, Keqi; Belov, Mikhail B.; Tolmachev, Aleksey V.; Udseth, Harold R.; Smith, Richard D.

    2005-12-27

    A method for introducing ions generated in a region of relatively high pressure into a region of relatively low pressure by providing at least two electrospray ion sources, providing at least two capillary inlets configured to direct ions generated by the electrospray sources into and through each of the capillary inlets, providing at least two sets of primary elements having apertures, each set of elements having a receiving end and an emitting end, the primary sets of elements configured to receive a ions from the capillary inlets at the receiving ends, and providing a secondary set of elements having apertures having a receiving end and an emitting end, the secondary set of elements configured to receive said ions from the emitting end of the primary sets of elements and emit said ions from said emitting end of the secondary set of elements. The method may further include the step of providing at least one jet disturber positioned within at least one of the sets of primary elements, providing a voltage, such as a dc voltage, in the jet disturber, thereby adjusting the transmission of ions through at least one of the sets of primary elements.

  3. Comparison of abundances, compositions and sources of elements, inorganic ions and organic compounds in atmospheric aerosols from Xi'an and New Delhi, two megacities in China and India.

    PubMed

    Li, Jianjun; Wang, Gehui; Aggarwal, Shankar G; Huang, Yao; Ren, Yanqin; Zhou, Bianhong; Singh, Khem; Gupta, Prabhat K; Cao, Junji; Zhang, Rong

    2014-04-01

    Wintertime TSP samples collected in the two megacities of Xi'an, China and New Delhi, India were analyzed for elements, inorganic ions, carbonaceous species and organic compounds to investigate the differences in chemical compositions and sources of organic aerosols. The current work is the first time comparing the composition of urban organic aerosols from China and India and discussing their sources in a single study. Our results showed that the concentrations of Ca, Fe, Ti, inorganic ions, EC, PAHs and hopanes in Xi'an are 1.3-2.9 times of those in New Delhi, which is ascribed to the higher emissions of dust and coal burning in Xi'an. In contrast, Cl(-), levoglucosan, n-alkanes, fatty alcohols, fatty acids, phthalates and bisphenol A are 0.4-3.0 times higher in New Delhi than in Xi'an, which is attributed to strong emissions from biomass burning and solid waste incineration. PAHs are carcinogenic while phthalates and bisphenol A are endocrine disrupting. Thus, the significant difference in chemical compositions of the above TSP samples may suggest that residents in Xi'an and New Delhi are exposed to environmental hazards that pose different health risks. Lower mass ratios of octadecenoic acid/octadecanoic acid (C18:1/C18:0) and benzo(a)pyrene/benzo(e)pyrene (BaP/BeP) demonstrate that aerosol particles in New Delhi are photochemically more aged. Mass closure reconstructions of the wintertime TSP indicate that crustal material is the most abundant component of ambient particles in Xi'an and New Delhi, accounting for 52% and 48% of the particle masses, respectively, followed by organic matter (24% and 23% in Xi'an and New Delhi, respectively) and secondary inorganic ions (sulfate, nitrate plus ammonium, 16% and 12% in Xi'an and New Delhi, respectively).

  4. Extraction and isolation of TPE from other elements on ion exchangers in aqueous and aqueous-organic solutions of phosphoric acid

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.; Stepushkina, V.V.

    1988-07-01

    The behavior of Am-Es and other actinides on anion and cation exchange resins in aqueous and aqueous-organic solutions of phosphoric acid has been studied in a wide range of concentration of various components of the solution. The sorptivity of transplutonium elements (TPE) on anion exchangers from dilute H/sub 3/PO/sub 4/ with a concentration less than or equal to 1 M in presence of organic solvents (alcohols, ketones, etc.) and on cation exchangers from concentrated H/sub 3/PO/sub 4/ has been found to be significant. The possibility of use of phosphoric acid solutions for isolation of TPE from Th, Pa, U, Np, Pu, and Zr and separation of TPE in different oxidation states in presence of a high-purity oxidant has been shown.

  5. Material/element-dependent fluorescence-yield modes on soft X-ray absorption spectroscopy of cathode materials for Li-ion batteries

    SciTech Connect

    Asakura, Daisuke; Hosono, Eiji; Nanba, Yusuke; Zhou, Haoshen; Okabayashi, Jun; Ban, Chunmei; Glans, Per -Anders; Guo, Jinghua; Mizokawa, Takashi; Chen, Gang; Achkar, Andrew J.; Hawthron, David G.; Regier, Thomas Z.; Wadati, Hiroki

    2016-03-07

    Here, we evaluate the utilities of fluorescence-yield (FY) modes in soft X-ray absorption spectroscopy (XAS) of several cathodematerials for Li-ion batteries. In the case of total-FY (TFY) XAS for LiNi0.5Mn1.5O4, the line shape of the Mn L3-edge XAS was largely distorted by the self-absorption and saturation effects, while the distortions were less pronounced at the NiL3 edge. The distortions were suppressed for the inverse-partial-FY (IPFY) spectra. We found that, in the cathodematerials, the IPFY XAS is highly effective for the Cr, Mn, and Fe L edges and the TFY and PFY modes are useful enough for the NiL edge which is far from the O K edge.

  6. A new N-hydroxyethyliminodiacetic acid modified core-shell silica phase for chelation ion chromatography of alkaline earth, transition and rare earth elements.

    PubMed

    McGillicuddy, Nicola; Nesterenko, Ekaterina P; Nesterenko, Pavel N; Stack, Elaine M; Omamogho, Jesse O; Glennon, Jeremy D; Paull, Brett

    2013-12-20

    Bare core-shell silica (1.7μm) has been modified with iminodiacetic acid functional groups via standard silane chemistry, forming a new N-hydroxyethyliminodiacetic acid (HEIDA) functionalised core-shell stationary phase. The column was applied in high-performance chelation ion chromatography and evaluated for the retention of alkaline earth, transition and heavy metal cations. The influence of nitric acid eluent concentration, addition of complexing agent dipicolinic acid, eluent pH and column temperature on the column performance was investigated. The efficiencies obtained for transition and heavy metal cations (and resultant separations) were comparable or better than those previously obtained for alternative fully porous silica based chelation stationary phases, and a similarly modified monolithic silica column, ranging from ∼15 to 56μm HETP. Increasing the ionic strength of the eluent with the addition of KNO3 (0.75M) and increasing the column temperature (70°C) facilitated the isocratic separation of a mixture of 14 lanthanides and yttrium in under 12min, with HETP averaging 18μm (7μm for Ce(III)).

  7. Lysozyme loading and release from Se doped hydroxyapatite nanoparticles.

    PubMed

    Wang, Yanhua; Hao, Hang; Zhang, Shengmin

    2016-04-01

    Element-substituted hydroxyapatite (HA) based nanocomposites have become a promising therapeutic material for improving bone defect repair. Selenium substituted HA nanoparticles can both induce apoptosis of bone tumor cells and enhance osteointegration. However, the effect of selenite ions on the proteins in combination with the HA nanoparticles remains to be elucidated. Here, we investigated the influence of selenium doping concentration on the loading and release of lysozyme (LSM) as a model protein drug. The selenium substituted HA-LSM composites with different doping concentrations were synthesized and characterized. The subsequent delivery of lysozyme was studied in a phosphate buffer solution (PBS). We found that selenium substituted HA-LSM composites with Se:P=10% showed the highest amount of lysozyme loading (41.7%), whereas the amount of lysozyme loaded in undoped HA nanoparticles was the lowest (34.1%). The doped selenium interacts with lysozyme molecules, which leads to the increase of β-sheet and unordered, and the decrease of self-association, α-helix and β-turns in protein structures. Moreover, selenium addition significantly slows the protein release from HA-LSM composites. The composites with Se:P=10% release lysozyme at the slightly slower rate among the samples with different Se doping concentrations. It also shows that the released lysozyme retains most of its enzymatic activity.

  8. Quick release latch for reactor scram

    DOEpatents

    Johnson, M.L.; Shawver, B.M.

    1975-09-16

    A simple, reliable, and fast-acting means for releasing a control element and allowing it to be inserted rapidly into the core region of a nuclear reactor for scram purposes is described. A latch mechanism grips a coupling head on a nuclear control element to connect the control element to the control drive assembly. The latch mechanism is closed by tensioning a cable or rod with an actuator. The control element is released by de-energizing the actuator, providing fail-safe, rapid release of the control element to effect reactor shutdown. A sensing rod provides indication that the control element is properly positioned in the latch. Two embodiments are illustrated, one involving a collet- type latch mechanism, the other a pliers-type latch mechanism with the actuator located inside the reactor vessel. (auth)

  9. Quick release latch for reactor scram

    DOEpatents

    Johnson, Melvin L.; Shawver, Bruce M.

    1976-01-01

    A simple, reliable, and fast-acting means for releasing a control element and allowing it to be inserted rapidly into the core region of a nuclear reactor for scram purposes. A latch mechanism grips a coupling head on a nuclear control element to connect the control element to the control drive assembly. The latch mechanism is closed by tensioning a cable or rod with an actuator. The control element is released by de-energizing the actuator, providing fail-safe, rapid release of the control element to effect reactor shutdown. A sensing rod provides indication that the control element is properly positioned in the latch. Two embodiments are illustrated, one involving a collet-type latch mechanism, the other a pliers-type latch mechanism with the actuator located inside the reactor vessel.

  10. Radioactive ion detector

    DOEpatents

    Bower, K.E.; Weeks, D.R.

    1997-08-12

    Apparatus for detecting the presence, in aqueous media, of substances which emit alpha and/or beta radiation and determining the oxidation state of these radioactive substances, that is, whether they are in cationic or anionic form. In one embodiment, a sensor assembly has two elements, one comprised of an ion-exchange material which binds cations and the other comprised of an ion-exchange material which binds anions. Each ion-exchange element is further comprised of a scintillation plastic and a photocurrent generator. When a radioactive substance to which the sensor is exposed binds to either element and emits alpha or beta particles, photons produced in the scintillation plastic illuminate the photocurrent generator of that element. Sensing apparatus senses generator output and thereby indicates whether cationic species or anionic species or both are present and also provides an indication of species quantity. 2 figs.

  11. Radioactive ion detector

    DOEpatents

    Bower, Kenneth E.; Weeks, Donald R.

    1997-01-01

    Apparatus for detecting the presence, in aqueous media, of substances which emit alpha and/or beta radiation and determining the oxidation state of these radioactive substances, that is, whether they are in cationic or anionic form. In one embodiment, a sensor assembly has two elements, one comprised of an ion-exchange material which binds cations and the other comprised of an ion-exchange material which binds anions. Each ion-exchange element is further comprised of a scintillation plastic and a photocurrent generator. When a radioactive substance to which the sensor is exposed binds to either element and emits alpha or beta particles, photons produced in the scintillation plastic illuminate the photocurrent generator of that element. Sensing apparatus senses generator output and thereby indicates whether cationic species or anionic species or both are present and also provides an indication of species quantity.

  12. Trace elements in dialysis.

    PubMed

    Filler, Guido; Felder, Sarah

    2014-08-01

    In end-stage chronic kidney disease (CKD), pediatric nephrologists must consider the homeostasis of the multiple water-soluble ions that are influenced by renal replacement therapy (RRT). While certain ions such as potassium and calcium are closely monitored, little is known about the handling of trace elements in pediatric dialysis. RRT may lead to accumulation of toxic trace elements, either due to insufficient elimination or due to contamination, or to excessive removal of essential trace elements. However, trace elements are not routinely monitored in dialysis patients and no mechanism for these deficits or toxicities has been established. This review summarizes the handling of trace elements, with particular attention to pediatric data. The best data describe lead and indicate that there is a higher prevalence of elevated lead (Pb, atomic number 82) levels in children on RRT when compared to adults. Lead is particularly toxic in neurodevelopment and lead levels should therefore be monitored. Monitoring of zinc (Zn, atomic number 30) and selenium (Se, atomic number 34) may be indicated in the monitoring of all pediatric dialysis patients to reduce morbidity from deficiency. Prospective studies evaluating the impact of abnormal trace elements and the possible therapeutic value of intervention are required.

  13. Mapping selected trace elements and major ions, 2000-2012, Mojave River and Morongo groundwater basins, southwestern Mojave Desert, San Bernardino County, California

    USGS Publications Warehouse

    Metzger, Loren F.; Landon, Matthew K.; House, Sally F.; Olsen, Lisa D.

    2015-01-01

    The population of the Mojave River and Morongo groundwater basins has grown rapidly during the last several decades, increasing from an estimated population of almost 273,000 in 1990 (Mojave Water Agency, 2004) to more than 453,000 in 2010 (Mojave Water Agency, 2014). Groundwater is the primary source of potable water in both basins (Mojave Water Agency, 2014). Previous studies noted elevated concentrations of several trace elements, nitrate, and total dissolved solids in groundwater in portions of the two basins (Christensen and Fields-Garland, 2001; Ball and Izbicki, 2004; Izbicki and others, 2008; Mathany and Belitz, 2009; Wright and Belitz, 2010; Dawson and Belitz, 2012; and Izbicki and others, 2012). Since 2000, the U.S. Geological Survey (USGS) has collected water-quality data annually from a network of wells and has provided quality-assurance for Mojave Water Agency (MWA) data that are stored in the USGS National Water Information System (NWIS) database. The new data and results from the joint State of California and USGS Groundwater Ambient Monitoring and Assessment (GAMA) program assessments of regional water quality (these data are also stored in NWIS), in combination with ongoing MWA/USGS groundwater-quality monitoring provide a timely opportunity for mapping of groundwater quality in the Mojave River and Morongo groundwater basins. The purpose of this report is to provide maps and time-series plots of concentrations of selected water-quality constituents (arsenic, boron, chromium-6, total chromium, dissolved oxygen, fluoride, iron, manganese, nitriate plus nitrite as nitrogen, total dissolved solids, uranium, and vanadium) in the Mojave River and Morongo groundwater basins using data collected by the USGS and MWA from 2000 to 2012. These maps and plots can be accessed on this website.

  14. Assessment of thermal gradient tube results from the HI series of fission product release tests

    SciTech Connect

    Norwood, K.S.

    1985-03-01

    A thermal gradient tube was used to analyze fission product vapors released from fuel heated in the HI test series. Complete deposition profiles were obtained for Cs, I, Ag, and Sb. The cesium profiles were complex and probably were dominated by Cs-S-O compounds formed by release of sulfur from furnace ceramics. The iodine profiles were simple, indicating that more than 99.5% of the released iodine behaved as a single nonvolatile species, probably CsI. Mass transfer coefficients for this species onto platinum were estimated to be 1.9 to 5.8 cm/s. Silver was probably released in elemental form, condensed to an aerosol, and captured by filters. Antimony was released as the element and reacted rapidly with platinum (or gold) as it deposited. Antimony profiles were calculated a priori with some success. A method was developed for isolating tellurium from platinum and mixed fission products in a form suitable for neutron activation analysis. The platinum samples were completely dissolved in acid (HCl/HNO/sub 3/), and the tellurium was precipitated on selenium carrier by reduction. Finally, tellurium was loaded onto Dowex 1X-4 ion-exchange resin for activation and analysis. Tellurium recovery was approx. 88%, and the theoretical sensitivity was approx. 30 ng.

  15. Synapsins Differentially Control Dopamine and Serotonin Release

    PubMed Central

    Kile, Brian M.; Guillot, Thomas S.; Venton, B. Jill; Wetsel, William C.; Augustine, George J.; Wightman, R. Mark

    2010-01-01

    Synapsins are a family of synaptic vesicle proteins that are important for neurotransmitter release. Here we have used triple knockout (TKO) mice lacking all three synapsin genes to determine the roles of synapsins in the release of two monoamine neurotransmitters, dopamine and serotonin. Serotonin release evoked by electrical stimulation was identical in substantia nigra pars reticulata slices prepared from TKO and wild-type mice. In contrast, release of dopamine in response to electrical stimulation was approximately doubled in striatum of TKO mice, both in vivo and in striatal slices, in comparison to wild-type controls. This was due to loss of synapsin III, because deletion of synapsin III alone was sufficient to increase dopamine release. Deletion of synapsins also increased the sensitivity of dopamine release to extracellular calcium ions. Although cocaine did not affect the release of serotonin from nigral tissue, this drug did enhance dopamine release. Cocaine-induced facilitation of dopamine release was a function of external calcium, an effect that was reduced in TKO mice. We conclude that synapsins play different roles in the control of release of dopamine and serotonin, with release of dopamine being negatively regulated by synapsins, specifically synapsin III, while serotonin release appears to be relatively independent of synapsins. These results provide further support for the concept that synapsin function in presynaptic terminals varies according to the neurotransmitter being released. PMID:20660258

  16. Risk analysis approach. [of carbon fiber release

    NASA Technical Reports Server (NTRS)

    Huston, R. J.

    1979-01-01

    The assessment of the carbon fiber hazard is outlined. Program objectives, requirements of the risk analysis, and elements associated with the physical phenomena of the accidental release are described.

  17. Active ion tracer experiments attempted in conjunction with the ion composition experiment on GEOS-2

    NASA Astrophysics Data System (ADS)

    Young, D. T.

    It is pointed out that to date six ion injection/tracer experiments have been attempted in conjunction with the GEOS-2 Ion Composition Experiment: three rocket borne Ba shaped-charge releases (Porcupine 3 and 4 and Ba-GEOS), one Li release, and two periods of operation of the Xe(+) accelerator on the SCATHA satellite. The characteristics of each of these six releases are outlined, and upper limits are placed on possible ion fluxes reaching GEOS-2. The order of magnitude of ion fluxes to be expected from each release is estimated, and it is shown that three of the experiments had no real chance of succeeding in the first place.

  18. Nitrogen release during coal combustion

    SciTech Connect

    Baxter, L.L.; Mitchell, R.E.; Fletcher, T.H.; Hurt, R.H.

    1995-02-01

    Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99% on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release rate relative to that of carbon and mass increases, with fractional nitrogen release rates exceeding fractional mass and fractional carbon release rates during devolatilization for high-rank (low-volatile bituminous) coals. At the onset of combustion, nitrogen release rates increase significantly. For all coals investigated, cumulative fractional nitrogen loss rates relative to those of mass and carbon passes through a maximum during the earliest stages of oxidation. The mechanism for generating this maximum is postulated to involve nascent thermal rupture of nitrogen-containing compounds and possible preferential oxidation of nitrogen sites. During later stages of oxidation, the cumulative fractional loss of nitrogen approaches that of carbon for all coals. Changes in the relative release rates of nitrogen compared to those of both overall mass and carbon during all stages of combustion are attributed to a combination of the chemical structure of coals, temperature histories during combustion, and char chemistry.

  19. Xyce release and distribution management : version 1.2.

    SciTech Connect

    Hutchinson, Scott Alan; Williamson, Charles Michael

    2003-10-01

    This document presents a high-level description of the Xyce {trademark} Parallel Electronic Simulator Release and Distribution Management Process. The purpose of this process is to standardize the manner in which all Xyce software products progress toward release and how releases are made available to customers. Rigorous Release Management will assure that Xyce releases are created in such a way that the elements comprising the release are traceable and the release itself is reproducible. Distribution Management describes what is to be done with a Xyce release that is eligible for distribution.

  20. Multi-elemental characterization of tunnel and road dusts in Houston, Texas using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry: evidence for the release of platinum group and anthropogenic metals from motor vehicles.

    PubMed

    Spada, Nicholas; Bozlaker, Ayse; Chellam, Shankararaman

    2012-07-20

    Platinum group elements (PGEs) including Rh, Pd, and Pt are important tracers for vehicular emissions, though their measurement is often challenging and difficult to replicate in environmental campaigns. These challenges arise from sample preparation steps required for PGE quantitation, which often cause severe isobaric interferences and spectral overlaps from polyatomic species of other anthropogenically emitted metals. Consequently, most previous road dust studies have either only quantified PGEs or included a small number of anthropogenic elements. Therefore a novel analytical method was developed to simultaneously measure PGEs, lanthanoids, transition and main group elements to comprehensively characterize the elemental composition of urban road and tunnel dusts. Dust samples collected from the vicinity of high-traffic roadways and a busy underwater tunnel restricted to single-axle (predominantly gasoline-driven) vehicles in Houston, TX were analyzed for 45 metals with the newly developed method using dynamic reaction cell-quadrupole-inductively coupled plasma-mass spectrometry (DRC-q-ICP-MS). Average Rh, Pd and Pt concentrations were 152±52, 770±208 and 529±130 ng g(-1) respectively in tunnel dusts while they varied between 6 and 8 ng g(-1), 10 and 88 ng g(-1) and 35 and 131 ng g(-1) in surface road dusts. Elemental ratios and enrichment factors demonstrated that PGEs in dusts originated from autocatalyst attrition/abrasion. Strong evidence is also presented for mobile source emissions of Cu, Zn, Ga, As, Mo, Cd, Sn, Sb, Ba, W and Pb. However, all other elements including rare earths most likely arose from weathering, erosion and resuspension of crustal material. These are the first such detailed measurements in Houston, the largest city in TX and fourth largest in the United States. We posit that such investigations will assist in better understanding PGE concentrations in urban environments while providing elemental data necessary to better understand

  1. Ion source

    DOEpatents

    Leung, Ka-Ngo; Ehlers, Kenneth W.

    1984-01-01

    A magnetic filter for an ion source reduces the production of undesired ion species and improves the ion beam quality. High-energy ionizing electrons are confined by the magnetic filter to an ion source region, where the high